Commons:Categories for discussion/2013/03/Category:Trams in Prague: Difference between revisions

Every tram in Prague has it's own category based on its fleet number, this means that the category for the Category:Škoda 15T in Prague just has a list of trams with the photos in there, many only have one picture. The same is true for almost all Category:Trams in Prague subcategories, it actually makes it really hard to find pictures, as you have to look through dozens if not hundreds of different categories. All of these individual fleet categories are then together in one mega category Category:Trams in Prague by registration number - which has 1,048 categories listed (one for each Prague tram), most with only one or two files or no files and just more categories. Is this really necessary? Can we move all photos of trams into the category of model, and not have them all sorted by fleet number? Liamdavies (talk) 05:44, 17 March 2013 (UTC)[reply]

This is something that should be done by intersecting categories. But I think that Commons has no such extension. Sinnamon (talk) 05:54, 17 March 2013 (UTC)[reply]

Pardon? Liamdavies (talk) 05:57, 17 March 2013 (UTC)[reply]

Sorry, I will try to explain. There is an "intersection" extension out there for MW software, it allows a person to say something like "find all images in category 'Trams in Prague' and 'Skoda 15T trams'" and to display such as a category. This would make categorisation (you only categorise once per a specific thing, and would allow people to find files that are as specific or as general as they wish. I hope it's a little clearer now. Sinnamon (talk) 06:00, 17 March 2013 (UTC)[reply]

https://www.mediawiki.org/wiki/Extension:CategoryIntersection Sinnamon (talk) 06:02, 17 March 2013 (UTC)[reply]

Ok, but with the lack of that extension what do we do? Is it acceptable that we have 1,048 categories - one for each tram vehicle in Prague? I would think it much better and easier to have all tram vehicles of the same type to be in one category, the current situation is hugely unwieldy and makes it really really hard to look for photos for articles. Is there a policy or convention on this? Liamdavies (talk) 06:06, 17 March 2013 (UTC)[reply]

I am not as knowledgeable as to know if there's a policy about that. But it does seem that, although with good intentions, somebody has gone overboard with categorisation. If there's only a single photo of each tram type, then it'd be much easier to simply put the type in the description of the image, and let the person to find that tram using Special:Search. But that is just my opinion. Sinnamon (talk) 06:34, 17 March 2013 (UTC)[reply]

This is exactly what I want to do, I want to put all pictures of one type/model/class into just one category (ie all pictures of 15Ts in Prague in Category:Škoda 15T in Prague), but I would like consensus or a policy to back me up. The user who categorised them all seems to be quite quick to move and I'd rather not do a lot of work and then have it all reverted. Also, it's not type, it just the actual vehicle number, there is no difference between any of the trams in Category:Škoda 15T in Prague except the number (maybe a few differences with the first couple, but the rest should be the same). It would be like categorising all cars in Category:Police automobiles in Australia by registration plate, it just makes it difficult to find pictures for articles. Liamdavies (talk) 10:26, 17 March 2013 (UTC)[reply]

Hi. I understand your reasons against this detailed categorization. However, you maybe undervalue the advantages and benefits.

• When you argue that "many only have one picture", you should not neglect the "many have several or tens of pictures" and "just every vehicle have its own photo". That time that most of individual vehicles have their own photo on Commons, there is the right time to create corresponding subcategories.
• The old Ringhoffer trams have no official type names, the fleet numbers are an useful instrument to systematize the photos.
• Some types of trams were manufactured through tens of years - although it is identic type, many details were successively changed (T3 from 1960s is a bitt different than T3 from late 1970s) and the fleet number sequence is a good way how to reflect it.
• Many photographs (even from transport fans) are not familiar with knowledge of tram types and subtypes. However, everybody of them should be able to categorize a tram by its sheet number, thereby indirectly assigns the tram to its type.
• Individual tram vehicles are not so anonymous and identical as you believe. Above all, advertisement coats and plasters make the vehicles very distinctive. Some vehicles are specific as prototypes, modified pieces, many pieces have almost 50 years of their unique history, endured reconstructions and modifications, accidents, transfers from one depot to another etc. etc. Detailed categorization enables to group or list individual vehicles by their subseries, common attributes, identic history etc. and allows to connect the pre-reconstruction identity with the post-reconstruction identity of individual trams.

I would be not in a hurry to apply this system on buses (which have substantially shorter lifetime period) but I think, this categorization of trams is very usefull and adequate to the current (and future) quantity of uploaded photos. The modular system of categorization is optimalized for detailed systematic classification. You can compenzate its disadvantages by gallery pages, paralel categorization by view (see Views of vehicles) or wait for new functionalities for more comfortable browsing of subcategories. --ŠJů (talk) 12:08, 18 March 2013 (UTC)[reply]

Hi, I understand why it's been done, but I don't think commons is suited for that level of categorisation. What you're talking about is far more suited to a database (all Melbourne trams are in a database called vicsig it's very good, but it's also much easier to use, and easily searchable). I am very versed in the differences and anomalies in different vehicles, please do not be mistaken on that. But... aside from the first 2 prototype 15Ts, they are the essentially the same tram with different numbers. The other differences you speak of could be dealt with through a simpler category system, all T3s should still remain in subclass categories, and AOA trams could be placed into a separate category too.

There are many useless categories, for example, why does this exist; Category:Tram_6138_(Prague)? Why can these two pictures; File:Pivni tramway.jpg & File:Nádraží Hostivař, 6815+6909.jpg not just be in the same category, ie Category:Tatra T3 in Prague - the second picture is the only picture in two categories; Category:Tram 6815 (Prague) & Category:Tram 6909 (Prague).

A much better way of sorting them would be to include the numbers into the description and/or file name so that they can be located through a search, or in the case of the file name, show up in order. I have never seen such a fragmented and convoluted system, categories are to sort and make files easy to find, not to hide and obscure the contents of commons. For example, on the first page of Category:Tatra T3 in Prague only 19 out of 200 categories actually contain a photo, the rest just contain more categories, it's a maze. Can someone more versed on category policy please weight in on this? Liamdavies (talk) 14:07, 18 March 2013 (UTC)[reply]

I've run Category:Trams in Prague through CatScan V2.0β and it found 3184 objects (pages, categories and files) and searched 1133 categories, this means that there are 1133 categories within Category:Trams in Prague to sort only 2051 pages and files, surely this can be consolidated down to about many fewer categories. Liamdavies (talk) 14:31, 18 March 2013 (UTC)[reply]

I've thought of a solution. We can convert all of the "Tram xxxx (Prague)" categories to hiddencats, so that one can still click a link and show all photos of an individual tram, and then ad the broader category ie Category:Tatra T3 in Prague, so images will also populate that category, and lower dramatically the amount of categories visibly nested in Category:Trams in Prague. Ideas? Liamdavies (talk) 14:42, 18 March 2013 (UTC)[reply]

I think, Commons should categorize on all relevant levels, not only on the higher ones. The adequate level depends (besides other) on amount of the uploaded photos (files) and subcategories. I think, more than 2000 photos are enough to be categorized thoroughly. Categories should sort the content systematically, not group hundreds of photos to one big dump. Categorization system of wiki projects is primarily modular, not by tags or keywords. Even if some pieces have only one or two photos still, there is useful to enable to find them (and to group the two photos together) - and moreover, many pieces have more photos.

I see no reason in converting these categories to hiddencats. They are standard item categories - just as categories of individual buildings, villages, people etc. They should be visible, properly categorized and not separated. "Hidden" mark would solve absolutely nothing. Category of an individual vehicle must be certainly visible and foundable in the category of the corresponding type, so the amout of subcategories would not drop by such action. If we want some "summary" view, we can wait for some tool to effective browsing of subcategories or create some paralel category branch (trams by view etc.) or overview galleries but we should not destroy or paralyse the current detailed categorization by number.

You are right that pieces of the newest types (Škoda 14T, Škoda 15T) have very short specific history (and only several of them have or had a specific advertisement coat or some specific equipment like WiFi), but it would be not desirable to differ categorizing standards for every type of tram. Btw, the type name is not so good visible on the vehicles as the fleet number, thus the number is more practical for the basic level of categorization. The simple unified system is very friendly for who is searching or uploading a photo of a real vehicle.

Category:Tram_6138_(Prague) is obviously not an useless category. It is not empty but it contain one subcategory, which means that we have no photo of this tram before the reconstruction and renumbering yet, but we have some its photos past the reconstruction. Do you cannot see the subcategory, or don't understand the effort to associate the older and the newer photos of identic piece? We would make great thanks to the creators of that precise categorization.

The files File:Pivni tramway.jpg & File:Nádraží Hostivař, 6815+6909.jpg are categorized by the visible trams and the trams are categorized by type. It implies from the basic principle of categorization: „Generally files should only be in the most specific category that exists for certain topic.“ Similarly, if we have a specific category for some king or president, the photos from such category are not categorized directly into the parent categories like "Kings of..." or "Presidents of..." I agree that modular categorization can be uncomfortable for some kinds of usage but it was chosen as the basic principle and have also many big advantages. --ŠJů (talk) 17:16, 18 March 2013 (UTC)[reply]

I get the idea that we are going to go round in circles, and that you very much like the current category scheme, and will oppose any changes at all. Is this a correct assumption? Liamdavies (talk) 03:01, 19 March 2013 (UTC)[reply]

I mean this is wrong way. Wikipedia is the encyclopedia, not the list of vehicles. Individual vehicles should man find on special pages. Wikipedia should bring encyclopedial information and it is surely not the picture of each vehicle of some type from the same angle. Try to find view on the roof of 14T! Next reason is that rules should be commonly applicable. One user has a collection of photos of about 1.000 different wagons ČSD Class Uacs. Should he place them here?--PetrS. (talk) 12:28, 19 March 2013 (UTC)[reply]

This is Commons not Wikipedia. Over here we accumulate media suitable for use on Wikipedia and its sister sites. It's not unusual to have more pictures to illustrate a topic than are actually needed. As such, I'm OK with the lowest level vehicle categories. What's really needed are some nice galleries showing off the pictures we have. Is there a script which will seed these galleries with the media we have? Railwayfan2005 (talk) 20:50, 19 March 2013 (UTC)[reply]

@Liamdavies. You force me to go round in circles again.

• I didn't enforce nor create this system (except for some historic pieces) but I understand and respect it (its benefits were explained above). I consider as unacceptable to destroy this big work and to pour hundreds of images back together into big mixed dumps. However, I would be not in a hurry for mass application of this system on buses, metro and railway rolling stock etc. (except for important or specific pieces).
• I understand and share our troubles with modular categorization but the solution is to create some tool for effective browsing of subcategories or create some paralel category branch (trams by view, details of trams by type - e. g. "Roofs of Tatra T14" - etc.) or overview galleries. I'm ready to support such constructive changes, but not any destructive changes. --ŠJů (talk) 03:07, 20 March 2013 (UTC)[reply]

 Support upmerge per nom. commons should not be used as a database system for image classification at this level of detail. 1000 categories to sort 2000 images is excessive. Use of better naming schemes would be preferred - I support simplifying the category split.--Obi-Wan Kenobi (talk) 05:25, 20 March 2013 (UTC)[reply]

 Oppose removing current category tree.  Support creating a parallel one. Commons definitely should be used to provide educational media, which is categorised to the detail that is required for the use. The problem is that there are two different uses: 1) A person searching for any good picture of a tram, 2) An individual looking for a very specific image. Current system already helps the second, but makes it almost impossible to work for the first. Category intersection or "category with all subcategories" view would resolve this problem, however, currently the only way forward does seem to be two (or more) different category trees, with images residing in both. Sinnamon (talk) 06:05, 20 March 2013 (UTC)[reply]

From what I'm seeing we seem to be getting close to consensus here. I think we currently have three choices: do nothing, move all files to tram model category, or have a system of parallel categerising systems. I feel that as others have said, the commons is meant to be about educational value, and no such value is found in the current system (or the categorising by number system for that matter), but would like to propose a middle ground possibility that I hope is most palatable for all.

What I suggest is that we move Category:Trams in Prague by registration number from Category:Trams in Prague to Category:Tram transport in Prague, we would now have two categorisation systems sitting side by side. First: Category:Trams in Prague which would have pretty much all the current categories, but they would be populated by pictures of that model of tram, I imagine it would look like this: (an indent signifies a level of nesting categories)

• Category:Trams in Prague

  Category:Tatra T3 in Prague -> Full of pictures of Tatra T3s in Prague

  Category:Tatra T3 driving school trams in Prague -> Full of pictures of Tatra T3 driving school trams in Prague

  Category:Tatra T3 service trams in Prague -> Full of pictures of Tatra T3 service trams in Prague

  Category:Tatra T3G in Prague -> Full of pictures of Tatra T3Gs in Prague

  Category:Tatra T3M in Prague -> Full of pictures of Tatra T3Ms in Prague

• (and so on for all tram models, treating sub classes separate and not nested)

And a second category Category:Trams in Prague by registration number -> populated as it is But... text would be added to the top of the page, indicating what number range each tram type belongs to, with a link to Trams in Prague by registration number. What I'm thinking could be added to the top would be something along the lines of this:

This category has all trams in Prague listed by fleet number. Their model type and number range have been listed below. For more information please see: Trams in Prague by registration number

Tatra T3 numbers: 6092 - 6992 (many of these vehicles have been rebuilt as Tatra T3M)

Tatra T3SU numbers: 7001 - 7020 (originally built for the Soviet Union)

Tatra T3SUCS numbers: 7021 - 7292 (originally built for the Soviet Union - some have been rebuilt as Tatra T3R PLF)

Tatra T3M numbers: 8005 - 8106 (rebuilt from Tatra T3)

Tatra T3R.PV numbers: 8151 - 8185

Tatra T3R.P numbers: 8211 - 8579

etc etc.

It would mean that all pictures of a type/class/model of tram are in one folder, while preserving and adding to the interpretation of the categorisation by number scheme. I would also like to add that the page Trams in Prague by registration number conveys all the information the current category system does, but is much more accessible, easier to understand, and navigate than a nest of categories we currently have. What are peoples thoughts on this? Liamdavies (talk) 13:32, 20 March 2013 (UTC)[reply]

At first I would like to thanks ŠJů, that he send me a notice with link to this discussion. I have no idea, why creator of this discussion didn't do this, but it looks really impolite for me…

I think, that system of categorization which uses registration numbers, is really useful, because there are many differences between trams in each type and this category tree is only possible way, how to find pictures of tram, which you want. For example special door opening systems in some T3SUCS or T3M, air conditions, three types of doors or another orientation system and outside displays in some 15T trams. Another reason are trams with advertisements etc.

I fully understand, that it is necessary to have a category with images usable into articles; because of this I created Category:Quality images of trams in Prague and Trams in Prague, where you can find best images…

If someone thinks, that it is really necessary to have category with all trams of one type, I think, that best idea is leave todays tree and create category like Category:Tatras T3M in Prague and put all pictures of T3M into this category (or add to all images Category:Tatra T3M in Prague).

But as was written above by ŠJů, categorization tree by registration numbers have much reasons and it is useful. I can understand that someone, who is not into trams this looks like mess and plenty of useless categories, but in fact mess is one category with 800 pictures of Tatra T3R.P.

So best idea is leave todays tree and built parallel categorization if someone thinks, that it is more useful than one category and gallery with pictures, which is possible use in articles. — Jagro (talk) 15:46, 20 March 2013 (UTC)[reply]

Jagro, I meant no offense to you, I just did was I was instructed with the template on who to inform and how. I will however start by saying that I understand trams very well and am very knowledgeable on the subject. Regarding your points: 1) The pages you list contain only 107 images out of over 2000, not good enough. 2) The searching you highlight is not possible, there is no sorting by door count, AC, or anything other than model type/subtype and vehicle number, both of these can be addressed by a single list. 3) You are greatly exaggerating the amount of pictures that would be in the category you used as an example, there would be less than half the number you give (some where around 390, which is only a couple of pages, quite manageable) and you're favoured system of over categarisation would still be around, every tram would still be in a cat by number. Every tram would be findable by number, but all photos would be grouped by model or concept (interior etc) rather than by number, finding pictures would be easier. The reason the number cats have to be removed from model cats is for policy: COM:OVERCAT forbids it. Liamdavies (talk) 16:16, 20 March 2013 (UTC)[reply]

Liamdavies, I try to understand your proposals. I'm not sure that I understand all your thoughts but the main of them show that you didn't comprehend some of the most basic principles of categorization. That's not a good ground for our discussions about our dilemmas.

You suggested to move Trams in Prague by registration number from Trams in Prague to Category:Tram transport in Prague. Did you really not comprehend the relation between these two categories yet? Category:Tram transport in Prague is the parent category covering all aspect of tram transport in Prague (trams, infrastructure, organization, staff, service vehicles etc.) and Trams in Prague is a specific subcategory for tram vehicles. Trams in Prague by registration number is apparently a category of tram vehicles and that's why it appertains certainly into Trams in Prague as its meta-subcategory. This your proposal is totally nonsensical.

Your draft of category scheme is a bit incomprehensible for me. What should mean "Category:Tatra T3 in Prague -> Full of pictures of Tatra T3s in Prague"? Are you proposing a renaming of the categories from standard simple names to more complicated ones? Are you trying to explain that Category:Tatra T3 in Prague should not include subcategories of Tatra T3 trams in Prague? Are you proposing that categories of Tatra T3 subtypes shouldn't be subcategories of the Tatra T3 category? I strongly oppose all three these proposals because they violate standard principles of categorization.

As I can see, you utterly didn't understand what is called "over-categorization". Over-categorization is not a term for too detailed categorization. The fact that some categories contain only one file or one subcategory doesn't base overcategorization. Over-categorization is a term for one kind of violation of modularity principle of categorization. Regrettably, just such overcategorization is proposed by you. If any image of tram is put into the category of this vehicle, the category of the vehicle have to be also properly categorized (by type etc.). When you categorize the image also directly by type, you are commiting exemplary overcategorization. If you are proposing to remove all categories of indivudial vehicles from the category of their type, such change would be a next flagrant violation of categorization principles and a nonsensical break of category structure. If we would implement this your proposal, the categories of individual vehicles would lose most of their sense and usefulness and the categorization of tram vehicles would become chaotic and unmaintainable (some of images would be categorized only by one way, some only by the second way). Strict application of modularity principle should prevent such chaos. The current system of categorization by fleet number is very simple, friendly and helpful even for easy maintenance.

Your proposal to add the explanation of number series by type at the top of category page(s) is reasonable and such overview can be helpful especially for any uploader/editor when he is creating a new category of individual vehicle and want to categorize it properly. However, such description have no impact to the category structure. A possible way how to make the categorization even more simply would be to remove the overview category Trams in Prague by registration number and to categorize the categories of individual vehicles only by type (a number would be searchable using this overview description) – however, IMHO also this category is useful and should be kept.

Jagro, your proposal to create Category:Tatras T3M in Prague (as a subcategory of Category:Tatra T3M in Prague?) is very nonstandard and such category name is not just clear. All categories of vehicles by type are intended for images of vehicles of the corresponding type but we use not plural of the brand name. The two category names proposed by you don't express the distinction you want to reach. This proposal is not a suitable way how to compensate (trick) disadvantages of modularity principle of categorization. The modularity is not a specific problem of trams but it concerns whatever item. If we have hundreds of photos from any town, uncategorized view of them is better for some usages, and detailed categorization structure by street, building or season is better for another usages. We should not solve this dilemma by overcategorization as you want to do. As was said above many times, the usable solutions are:

• to create "category with all subcategories" view as a systematic software solution. I think, such functionality is urgently required for all types of categories (not only trams).
• to create desired subcategories by view or by part (Interiors of Tatra T3, Headlamps of Škoda 14T, Doors of Tatra T3, Front views of Tatra KT8D5 etc.) - some of such categories rather at the worldwide level rather than at the Prague level. --ŠJů (talk) 00:23, 21 March 2013 (UTC)[reply]

ŠJů, stop telling me I don't understand, or don't know. It's insulting and patronising. There is a huge difference between understanding and agreeing. I understand why you want it I just don't agree. But despite that, I am trying to think of ways to make your system work, I don't feel the same can be said of you. You are not giving helpful ideas, just rubbishing others and bringing up off topic ideas, like a category of tram roofs (which I haven't asked for and don't want). I understand COM:OVERCAT, you just didn't understand what I meant(I could have said it better, sorry). We can't have all photos of Tatra T3s in Category:Tatra T3 in Prague AND have all of the Category:Tram XXXX (Prague) categories in there as well, that is against COM:OVERCAT.

When I say "Category:Tatra T3 in Prague -> Full of pictures of Tatra T3s in Prague" I mean that the category named "Category:Tatra T3 in Prague" would be full of pictures of Tatra T3s (but NOT subclasses) and so on.

I would like you to answer this one question (yes or no please), would you be ok with a category that has all the photos of a certain type of tram in it, for example a category that has all the photos of Prague Tatra T3s in it? This is what I and others want, a category of tram roofs is not what I want, or what I think is proper, that's not to say you can't do that, I don't mind, but what I want is ONE place that contains ALL the photos of a certain type of tram. If you oppose this (and just oppose this, other category issues can be sorted out later) please state why, also please be concise, you don't need to insult me or write 1000 words, just one paragraph outlining your problems would be sufficient. If we can get some level of agreement on this one simple issue, then we can work out how to make that happen, if you don't agree I feel we are not going to reach a conclusion and will bring this up at Commons:Dispute resolution and seek outside mediation. Liamdavies (talk) 06:22, 21 March 2013 (UTC)[reply]

Liamdavies, the principles that

1) a subitem have to be a subcategory of the higher item

2) a file or category should be properly categorized into the most specific categories that fits them

3) categories are defined by item and contain both files and categories which appertain to the item

are bacis principles of wiki categorization of Commons. It is not some "my" system but system of Commons. Staying on these principles should not be called "insulting" or "patronising". Implementation of your proposals would severely disturb standard logic of categorization. I understand that the modular system of categorization have its disadvantages. However, it's not a sufficient reason to break, violate and ignore the system. I understand that the detailed categorization of trams is not only useful but also complicating for some kinds of usage. Such categorization is maybe too detailed but not incorrect nor nonsensical, unlike your proposals. I'm convinced that advantages of systematic detailed categorization of hundreds photos of Prague trams are not negligible and disadvantages are not so grave and eccentric that would be a reason for destruction and depreciation of this big work. If some vehicle have its own category, then the category have to by properly categorized by type of vehicle and all the inclused photos must not be categorized directly by type, because they are categorized through the category of the vehicle and the direct categorization would be exemplary overcategorization. I'm conscious that such overcategorization (to pour photos from all subcategories to one big unstructured group) is attractive and invited for you (and maybe, sometimes also for me) but such solution is fundamentally incompatible with categorization principles which prefer structured content and refuse overcategorization. (ONE place really should contain ALL the photos and subcategories of a certain type of tram, but it doesn't mean that the photos shouldn't be in appropriate subcategories.) Your desire should be fulfil rather by some software tool which would enable to browse subcategories in such way. If you would understand the above written arguments promptly, we must not to repeat them in circles in 1000s words. --ŠJů (talk) 12:45, 22 March 2013 (UTC)[reply]

This is a problem that we encounter often and that is not fully recognised. Basically, technical people want the most precise and deep categorisation as possible. Many other people just want big categories as to be able to do visual search. While tools like catscan (tab) can help, it is still not always very practical. And indeed, the more specialised the categories are getting, the more problems one has with "tourist" users that probably need hours to find out in what categories their "tram image" need to be categorised correctly and completely (there is hopefully only one single tram operator, so it could be worse ;). We've got very long discussions on that in Category:Churches in Belgium, and in many other heavily populated categories. The problem often gets worse because of COM:OVERCAT fundamentalists. So far, the best compromise we could come up with is:

• Keep the main category just for all (visually appealing) images, so all people can categorise and find them without any structural and specialist knowledge.
• Put the specialists category aside by grouping them in "item by xxx" categories.

This is not perfect as you don't necessarily want on the top level technical details of components or interiors, but as stated, it is a compromise. In the past, we have already discussed ideas to be able to tag some images as most representative/best/postcard type/... and to allow category displays to filter on that, but software development on wikipedia seems to be halted since years, at least on Commons. Note that we have very often a similar problem to create long flat lists (people by name, ships/aircraft by registration number, ...), but this is easier to solve with "xxx by yyy" categories. Alternatively, one could think of a category called "trams running in Prague operated by xxx operator", as to avoid overcat fundamentalists. --Foroa (talk) 18:21, 22 March 2013 (UTC)[reply]

• Place each image into both <tramnumber> in Prague and < big cat > trams in Prague, even though one is a subcat of the other. Ignore WP:OVERCAT where it is interpreted that no item should ever be included in a transitive supercategory. The reason is that each category here has a different use case: < big cat > is something like the tram model type, route or location (useful to many groups), whilst <tramnumber> is for tram-spotting individuals. Not my interest, not something I'd put interest into categorising (for mundane trams at least), but nor should I dismantle someone else's work in building such a category tree.

As noted at the top, MW has many extensions such as DPL for making categories more powerful. However they won't be happening on WMF projects for good performance reasons. Sadly there's also a problem at WP especially, where categories are neither understood, nor used well. Andy Dingley (talk) 22:10, 22 March 2013 (UTC)[reply]

Thanks for the input, I think you're both thinking a little to broadly, having all photos of all trams in Prague in one category would be unusably big, and finding good images would be just as hard as know due to information overload, Category:Churches in Belgium looks a little to broad for what I want. There would be 12 pages of images! I want one place where all photos of just one tram type are located, so I want all 140 images of Prague 15Ts to be in the category Category:Škoda 15T in Prague. I don't care one way or another if they are also categorised by fleet number, the reason I wanted to upmerge was to avoid COM:OVERCAT, that is the same reason I have proposed to move the fleet number categorisation system to another tree. But everything I have said has been slammed, I don't feel that ŠJů wants to discuss anyone of having all the photos of all the same type of tram in one place. If people think it is ok to COM:OVERCAT to make the images viewable in both cats I'm fine with that. Is there a way we can get BOTS to do this work? Or must it be done manually? I'd also like to add that cat scan seems quite broken for displaying images, only a hand full show up. Liamdavies (talk) 05:23, 23 March 2013 (UTC)[reply]

Foroa, the systematic overcategorization proposed by you is not a compromise but disabling and devaluation of the current system. One of its main functions is that every vehicle can be simply and infallibly categorized by type through the fleet number. Such categorization of images is very easily usable also for non-experts. Duplication and shattering of the category structure would bring only chaos - some images would be categorized only by the first system, some images only by the second one, as is typical for disorganized duplicite categorization. That's why the categorization should be modular and overcategorization is generally disapproved. I'm not a COM:OVERCAT fundamentalist – in some cases overcategorization is useful and harmless, but this is evidently not such case. I absolutely understand that overcategorization can be attractive and tempting for many users in many cases but this knowledge we have had even when the rule against overcategorization became received. Modular categorization is a bit uncomfortable for some types of usage but chaos is not an acceptable alternative. If the detailed categorization by fleet number would be completely meaningless and purposeless, I would also support to destroy and remove this level, but this is not such a case. --ŠJů (talk) 10:16, 27 March 2013 (UTC)[reply]

You obviously did not read what I wrote; it remains a fact that categorisation tends to go deeper and deeper, thereby hindering and rendering it sometimes useless for the generalists' needs, especially in regards with visual search. What this discussion has shown as well, is that no matter what solutions we will try to find, it will never cover the needs of all users. Obviously, we need more dynamic tools. For me, Catscan works like a charm (if all toolservers are running correctly), when it can stay below 1000 images (an old restriction for systems 10 years ago). --Foroa (talk) 14:50, 27 March 2013 (UTC)[reply]

As ŠJů notes, cat by tramnumber is useful because it's often clear (although not for most photos taken some time ago, as these numbers aren't always obvious) it's certainly unambiguous and it also has a strong implication for model number. So the Škoda 15T in Prague category begins to approach being a meta-cat. However it would still do nothing for trams by location, or even by route. Andy Dingley (talk) 10:43, 28 March 2013 (UTC)[reply]

Interesting discussion. If I may make some suggestions: Put the unidentified trams (no fleet number) in a higher category. No need to have "unidentified" categories. I also have problems with tram stop categories, wich are useless without local knowledge. A handy category would be by tramline number wich are more easily researched (trammaps etc). Examples: (Basel tram line 10, Basel tram line 8). But please dont make it a list of tram stop categories. Smiley.toerist (talk) 10:04, 31 March 2013 (UTC)[reply]

For purposes of maintenance, there is useful to distinguish images which were checked but are not simply indentifiable and images of trams which can be simply identifiable but were not sorted in depth yet (or have not their own subcategory yet). I think, such conception of categories of unidentified subjects is standardly used in case of geographical categories, bionomic categories, categories of vehicles etc. and is proven and very useful. "Unidentified" (in the category name) means "checked but the identification was not succesfull yet", "not simply identifiable".

Categories of tram lines would be also possible (for the future) but i think, Prague tram lines have not so distinctive specific identity to be urgent to create their categories. However, its possible for the future. The individual vehicles are more tied to their depot than to the line (but also the category "Trams in Prague by depot" would be not useful enough to be needed).

As regards Prague tram stop categories, they should be categorized also by street name & tram track section and the streets and tram track sections should be categorized by Prague district etc. Tram lines in Prague are often changed and are not so stable to be used as a skeleton of tram stop categorization. I think, Category:Tram tracks in Prague is a good base for localization of tram-related images and I feel no need of split their content to with-trams/without-trams subcategories. For the future, we can use some stop lists with links like here in railway track category or create some interactive map as a navbox. --ŠJů (talk) 10:22, 25 April 2013 (UTC)[reply]

I arrived lat to the party, but apparently the suggestion of removing the fleet number categories was dropped, or at least postponed — good!

It always frustrates me a lot when someone demands that the work of other editors should be undone because they cannot find their pretty pics — users who think that 2000 images all in the same category is a good thing because they can “browse” it (typically flying away contented with the 1st shiny object before it even reaches "B"). The problem here is not having a category for each vehicle — that is indeed part of the solution (only a part), the problem it solves being that we have 2000 known images of Prague trams. However, while the number of such categories will only grow as new photos are tagged (or when the city enlarges its fleet), the number of photos to be categorized will grow — a lot! Those 3000 could be 30000 in 10 yrs, because new images are added, uncategorized images are tagged, and old images fall in PD — and then instead of an average of 2 images in each category, you’ll have 15 or 20.

The rest of the solution is to add more metacategories under the main (take a look at this: Category:Trams in Lisbon, still not perfect, but going there) — sort them not only by fleet number, but also by model, route, date, time of the day, time of the year, location, status, attitude, et c., et c. Each photo should have a dozen such categories, and the pages for those categories will allow any kind of search to be made, filtered to oh so many kinds of preset descriptions. (Should some still just want to be fed an unfiltered slideshow of Prague trams to gaze at, it is already here.)

-- Tuválkin ✉ 13:54, 26 August 2013 (UTC)[reply]

Tuválkin, you misunderstand what I was requesting. No where did I request that all 2000 images be dumped into one huge category, that would be stupid. What I want is for each image to be in a category for its class, so that one can view all Skoda 15Ts operating in Prague, rather than have to trawl through 43 categories to look at the 148 images they contain. An example (on a smaller scale) of what I'm requesting is at Category:Trams in Melbourne by class. Conversely I would point to Category:Cable cars in San Francisco to show what an unorganised mess, riddled with OVERCAT this overly precise scheme becomes when there is no one to maintain it. Liamdavies (talk) 15:10, 26 August 2013 (UTC)[reply]

I’m glad you don’t want to remove the fleet number categorization after all. It would be a shame to have to redo all that categorization work again whenever we have 2000 images of Skoda 15Ts in Prague. Seriously, I think that COM:OVERCAT does not apply in these cases, although IMO a hidden cat (Category:All Skoda 15Ts) should be created for this. -- Tuválkin ✉ 23:38, 26 August 2013 (UTC)[reply]

I don't care if the images are have a cat for their number or not, my main problem is that the whole tram by registration number cat tree is more category that file. All it's function could be done by a single page. In fact we already have that page -> Trams in Prague by registration number, this page fulfils all the duties that the whole tree does. And yes, COM:OVERCAT is/would be a problem, as I said look at Category:Cable cars in San Francisco. Liamdavies (talk) 10:26, 27 August 2013 (UTC)[reply]

As appeared, you didn't understand that too detailed and systematic categorization is not COM:OVERCAT. COM:OVERCAT is exactly that what you demand: to use any less specific category instead of the most specific category (in addition, you try to disturb logical modular structure of categorization). I undestand that many users like overcategorization but it is not good solution and is not recommended generally. You should rather request more effective tools for browsing and display of subcategories. --ŠJů (talk) 00:05, 28 August 2013 (UTC)[reply]

ŠJů, stop telling me I don't understand things, when you have clearly misread what I'm saying. I'll go over it again: Tuválkin said: "I think that COM:OVERCAT does not apply in these cases" I responded: "yes, COM:OVERCAT is/would be a problem" (meaning that yes, having photo in both parent and child cat is COM:OVERCAT, and would be a problem, clearly that means that I understand), and then I additionally gave an example of where this style of categorisation has broken down, and is now in a mess of COM:OVERCAT: "as I said look at Category:Cable cars in San Francisco." It would be helpful if you would not simply tell me that I don't understand all the time (you have done that several times in this thread), it's patronising to be told that you don't understand, it's like someone telling you you're to stupid to have a view. Would you reread what I have said, and please either strike-through your incorrect statements, or offer an apology? Liamdavies (talk) 05:24, 28 August 2013 (UTC)[reply]

When two or more people don't achieve identic posture, it's important to recognize whether they don't understand each other or whether they understand but assert different solution only. If your current problem is that "the whole tram by registration number cat tree is more category that file", it is a false problem. If the content is categorized, it should be categorized systematically, not randomly. When some item is categorized "by country", we create often also some country categories for one or two images. The fact, that the categories of nowadays trams are structurally joined with categories of identic trams before their reconstruction and renumbering, is also a clear benefit. Don't waste our time with decimation of this big work. I understand and share your problem with too fragmented content but up to now, none of your proposals was compatible with basic principles of categorization. Such solution could be to remove all fleet number categories but as was said here, hunderds of images of identic type shouldn't be poured together to one unstructured heap. Maybe I also don't understand you: what OVERCAT problem you see in Category:Cable cars in San Francisco?

The real problem is that Commons doesn't offer an effective tool to display images from subcategories. We should strive to solve that problem. I believe, we should not solve the problem with unsystematic methods like overcategorization (a flat category for the type) or violation of modular principle of categorization (to not categorize categories of individual trams by their type) or replace the functional category structure with a "single page". --[[User:ŠJů (talk) 17:54, 28 August 2013 (UTC)[reply]

I have never suggested a random structure for categorisation, I think you fail to fully understand what I am saying. I understand your points, but you fail to understand mine. If you don't see an overcat problem at Category:Cable cars in San Francisco it means you haven't properly had a look. Look again, and this time rather than actually opening the cat, saying all good and closing it - look. Liamdavies (talk) 14:45, 29 August 2013 (UTC)[reply]

I had a look to Category:Cable cars in San Francisco and I see no overcategorization in the category structure not even overcategorized images. Could you specify what you consider to be overcategorization? Are you sur you understand what "overcategorization" is? --ŠJů (talk) 22:10, 29 December 2013 (UTC)[reply]

Wow, you must have looked really hard. The second image: File:11 Cable Car on Powell St, SF, CA, jjron 25.03.2012.jpg is clearly overcat, as are many many more. Either you aren't even trying and are just paying lip service or think I am an absolute moron, or both. Liamdavies (talk) 18:13, 8 January 2014 (UTC)[reply]

No comment yet ŠJů? Do you not understand? Maybe if I spell it out: you see (if you open your eyes and actually click on links) the image File:11 Cable Car on Powell St, SF, CA, jjron 25.03.2012.jpg is in both Category:San Francisco cable car no. 11 and Category:Cable cars in San Francisco (as are many others) , this is COM:OVERCAT. You may not understand due to either: being so pig headed as to think everything I write is wrong; or you are a complete moron - your choice, which is it? I understand that actually pretending to take what I say seriously may be difficult, as is investigating anything I point out, but please bear with me, or do you not understand? Liamdavies (talk) 14:34, 9 January 2014 (UTC)[reply]