A guide to Tags

Each MATLAB Answers Question may be assigned one or more "tags". But what are tags? Why are they useful? And which tags are the best to use?

"Tags" are words, or abbreviations, or short phrases that can be associated with Questions. Tags represent Question categories, or subject areas, or technology areas. Tags can be searched on, to find Questions related to the same topic.

By reviewing Questions in a category you are interested in, you may find a solution for your own query, or you may find inspiration for approaches to try.

When you assign appropriate key tags to your Questions, you increase the chances that people with experience in the topic area will find your Question, and either respond to you or learn from your Question and the discussions that follow. It is not uncommon for people with particular subject expertise to look at a Question's tags more than at the Question's title.

Sometimes the tags to use are obvious, such as tagging an FFT-related question with "fft". But sometimes the tags to use grow through popular use, when there are alternatives. Good tags should be easy to remember and closely related to the topic.

The Answers below list some of the tags in common use, and their meanings.

[Walter Roberson]

Please contribute common tags, or clarify meanings, or rephrase, or propose categories or suggest movement within categories.

This is not intended to be a complete list of tags, ever, but for any particular subject area it would be nice if it covered the most important or most commonly used tags -- or at least gave guidance for preferred forms of tags that people are more likely to enter differently.

[Walter Roberson]

I am thinking of adding

& Tag Glossary

to the title of this Question. It isn't quite a glossary and is not intended as one at the moment, but it is starting to look like one...

[Yash]

its a very nice thing and very good initiative taken by an active member of the forum.

[Kent Millard]

Terrific resource!

Thank you Walter.

[Walter Roberson]

I was thinking this morning, that to keep from duplicating the entire MATLAB function list, and keep the effort required for this thread manageable, that perhaps we should not bother to list tags that are MATLAB routine names, not unless the tag also has a broader meaning. For example, "plot" can be broader than "plot()".

What do people think?

[Jan]

What is the purpose of this thread? Do we collect a list of tags in common use? Or do we try to organize the usage of tags in the future?

[Ryan]

how about a statistics section?

[Image Analyst]

When you start typing a tag, it already gives you suggestions of tags used in the past, so I think people will just use those if they like the tags and I don't think they will come to this thread to check beforehand on the proper tag to use. Though I think editors should be able to modify the list. For example, we don't need both "digital image processing" and "image processing" - some people even pick both of them.

Answer 1

[Walter Roberson]

Tags dealing with the tone or manner of Questions

Tags are sometimes used to indicate something about the form or tone or manner of a question, rather than about the Question itself. These tags are usually applied by people who read the Questions. A few the tags people apply are more factual than anything, but some of them hint that the poster should improve the way the question was written.

• "doit4me": indicates that someone feels that your Question is asking people to solve your problem for you, or if your Question is interpreted to have been written like an order rather than a request. Your Question will likely be tagged with this if you ask for code without showing an attempt to solve the problem yourself. Homework tagged with "doit4me" will seldom be answered. If your Question gets tagged with "doit4me" it is advisable to rephrase the question to show your efforts, and to ask questions about a portion of the topic rather than imply you expect someone to show you how to do everything
• "homework": indicates that someone assessed the Question to be about a class assignment or a class project (such as a final-year project). This is sometimes used to signal that it is inadvisable to give direct solutions to the question where teaching is more appropriate than a direct solution. It is also used to signal Questions in which the asker copied directly from the assignment and appears to expect other people to do the assignment on their behalf. Some volunteers choose to skip homework Questions, but other volunteers choose to give longer more explanatory responses to improve understanding of the subject matter, and tend to be more patient when they know the person asking is a student. Thus a tag of "homework" is not necessarily a bad thing. However, the volunteers tend to dislike when homework questions are not acknowledged as being direct homework questions; and if direct copies of an assignment are posted without the asker showing any work, then the Question will usually receive no useful responses.
• "no attempt": indicates that the poster does not appear to have made an attempt to solve the problem by them-self. Volunteers tend to skip "no attempt" questions. If your Question gets tagged with this, then you should edit the Question to demonstrate that you have made efforts to solve the problem. The volunteers would rather show you how to fix code that needs improvement than to hand you an unearned answer. If your posting gets tagged both "homework" and "no attempt" then you have a lot of re-writing to do.
• "no_details": indicates that the Question was found to be too broad or too brief to give a useful answer.
• "no question": indicates that the Question left out actually asking anything. Sometimes this is just an accident, overlooked because the asker was concentrating on explaining the problem, but sometimes the tag hints that the Question was interpreted as being a demand rather than a request. "homework" and "no question" and "no attempt" as a trio are usually often added to Questions where the asker posted a homework question without adding anything else, and thus is giving the implicit order to "Do my homework for me!"
• "retag": indicates that the poster has been asked to read this Guide and add meaningful tags to their Question (e.g., if the only tag added was the useless "matlab") Please do not add this tag "retag" simply as a signal that the Question needs better tags: ask the poster for better tags before adding this one. This tag is used to make it easier for editors to track which Questions are waiting on the poster to re-tag them, reducing redundant checking of Questions
• "sendit2me": indicates that the Question asks for people to email answers or code. Some volunteers may choose not to respond to such Questions, and other volunteers will ignore that portion and respond on the MATLAB Answers system instead. For best response, avoid asking or implying that people should send you solutions instead of posting them.
• "urgent": indicates that the poster asked for high-priority response. These upset volunteers for many reasons. If one of your Questions is tagged with this, you should very likely edit your question to remove indications that you are asking for special consideration.
• "energizer bunny": indicates that the question and response sequence is going on and on and on, with no end in sight.

[Walter Roberson]

In this original form, this is pretty dense visually, and I suspect the people that need this section the most would be the least likely to read it carefully. Should I put empty lines between clauses ?

[Jan]

I suggest a common separator style for "no_details", "no attempt" and "no question". Do we prefer spaces or underscores?

[Walter Roberson]

I find the underscore style different from what everything else uses, so I would prefer the space style.

At the moment, there are about 110 no_details, 41 "no attempt", and 63 "no question", so either way I would have MATLAB Central has a bulk tag-changer. I can be pretty persistent in fixing those kinds of little details, but given the nature of those tags, if I review all those questions (in order to manually edit), I worry for my blood pressure

[Daniel Shub]

This is building on something Jan said someplace else and I agree with. I think we should remove the majority of these tags and replace with a flagging/closing of the question. The only ones I am not sure of are retag, urgent, and energizer bunny. I think flagging, but not closing, is appropriate for retag. I am not sure what to do about urgent and energizer bunny.

[Walter Roberson]

These days I close "urgent" pretty much as soon as I find them.

[neelofar safdar]

hi..can anyone help me in running bipolar fuzzy TOPSIS using MATLAB

[Walter Roberson]

That does not appear to be contribution about appropriate use of Tags. You should create a new question for that, and indicate there what you have done so far.

[Rik]

Post a separate question and make it specific. Show what you tried and how it is different from your expected results.

Answer 2

[Walter Roberson]

Tags to Avoid Using

• long phrases: Do not use the tag area to ask a question, only to establish categories.
• numbers by themselves such as "1". Possible exception: well-known part numbers such as 80386
• periods, or any other sequence of symbols without any letters
• "matlab": The entire resource is about MATLAB, so it can be assumed.
• "simulink" and other product names; put these in the Product field instead.
• "error": This is too common to be useful. Exception: if you are discussing the MATLAB error-signal generation function, tag with "error()"
• "help": This can be assumed. Exception: if you are discussion the MATLAB help function itself, tag with "help()"
• "matlab code": This is too common to be useful.
• "problem": This is too common to be useful.
• "urgent" or "emergency". These upset volunteers for many reasons and the volunteers tend to instead go and do something more fun like re-arranging their sock drawer.
• A specific person's name. If a particular Question looks Interesting to the particular person, they will (eventually) read it. Naming the person puts uncomfortable pressures on the volunteers and tends to create hard feelings. Naming a person also tends to discourage other people from responding.
• Your own name. You can use the "My Questions" link to find your own Questions.
• "plz" or other text-message abbreviations.
• do not include "#" or "@" at the beginning of a Tag. These are not Twitter hash-tags

Also, if you are wanting to tag with a MATLAB release number, please use its "R name", such as R13 or R2011b, rather than its version number.

Answer 3

[Walter Roberson]

Searching Tags

To search on a tag, you can click on the tag name where it appears in a summary list of Questions, or when a Question is being displayed. An index of Questions with the same tag will be displayed.

If you know the right spelling of a tag, you can give the tag directly in the Answers search box, with the prefix tag:, such as tag:tutorial . If there is a space in the tag, enclose the tag in double-quotes in the search box, such as tag:"image segmentation" . Spelling counts, but the search is not sensitive to upper or lower case.

If you only know part of the name of the tag, you can use asterisk as a "wild-card" in the Answers search box. For example, to search for all of the IEEE standard power-bus systems, you can search on tag:"ieee*bus" . This will match "ieee 30 bus", "ieee 6 bus", "ieee 57 bus" and the others.

Answer 4

[Walter Roberson]

Tags dealing with the kind of Question

• "discussion": indicates a Question intended to collect viewpoints on a topic, rather than looking for a specific solution.
• "how-to" or "howto" [needs standardization]: similar to a tutorial, but is usually shorter and about how to do something specific in MATLAB.
• "matlab answers": indicates the Question is about the features or facilities of the MATLAB Answers system itself.
• "meta": indicates the Question is about the MATLAB Answers forum itself. It can be information or questions on how to use MATLAB Answers, or it can be dialog about the Answers system, such as the wish-list.
• "tutorial": indicates a Question intended to show ways undertaking a process, especially something involving the MATLAB Answers system itself. May also indicate a Question which has links to resources (especially tutorials) on a topic

[Jan]

"meta" includes "matlab answers", but the latter might be confused with the frequently used, but meaningless "matlab" tag.

[Walter Roberson]

"matlab answers" has been used relatively cleanly. It means something distinct from "meta" to me, but I am not sure what the difference is at the moment.

Answer 5

[Walter Roberson]

Creating and Editing Tags

When you first create a Question, you should add some relevant tags in the Tag input area below the Question input area. The tags entered can be altered later. The tags you enter will be converted to lower-case. Separate tags with commas (not with semi-colons). Do not use # in front of the names.

You can use a tag phrase that did not previously exist, creating your own tag, but if you are discussing a common topic, it is much recommended that you use the existing tags for the topic

As you type in your proposed tag, if you pause a bit, the Answers system will search many of the existing tags and show you matches. This helps you to retain consistency with tags other people have entered. Tags that have not been applied much before will not be suggested. The details are not known, but it appears that tags will be included in the search once they have been used some 5 to 10 times.

If you have a Answers Reputation of 5 or more, then you can add tags to any Question, by clicking on the "Add/Edit Tags" link in the top right of the Tags display of Questions. This will expand the Tag area into an input area in which you can enter new tags.

If you have a Answers Reputation of 50 or more, then you can remove tags from any Question, by click on the "Add/Edit Tags" link in the top right of the Tags display of Questions, or by clicking on the red circle shown directly after the tag.

Answer 6

[Walter Roberson]

Tags dealing with filters

• "fir": indicates Finite Impulse Response filters
• "iir": indicates Infinite Impulse Response filters
• "butterworth": indicates Butterworth filters
• "fdesign": pertains to the Filter Design routine fdesign()
• "adaptive filter": pertains to adaptive filters
• "notch filter": pertains to notch filters

I do not know at the moment what the consensus name is for low-pass or high-pass filters ("lowpass" ? "low pass"? "low-pass"? With or without "filter"? Is "filter" usually written in the plural?)

Also to be resolved: "filter" vs "filters"

[Jan]

I suggest to use the singular for all tags: While it is not the nicest choice sometimes, it is easy to apply and to remember.

[Walter Roberson]

The wikipedia approach? No final "s" unless the final "s" changes the meaning rather than simply creating the plural ?

Test case: robotics vs robotic . The "s" makes it into "the study of", not the plural of "robotic"

Answer 7

[Walter Roberson]

Tags dealing with Communications Systems and Communications Theory

• "usrp": Universal Software Radio Peripheral
• "arithmetic encoding"
• "arithmetic decoding"
• "ber": Bit Error Rate
• "snr": Signal to Noise Ratio
• "mimo"
• "lte": Long Term Evolution (wireless standard)
• "ofdm": Orthogonal frequency-division multiplexing
• "fskmod": Frequency-Shifted Key Modulation routine fskmod()
• "pskmod": Phase-Shifted Key Modulation routine pskmod()
• "qammod": Quadrature Amplitude Modulation routine qammod()

Answer 8

[Walter Roberson]

Tags dealing with Differential Equations

• "ode15s", "ode23", "ode23s", "ode23t", "ode45", "ode113": references to the Ordinary Differential Equation routines of the same names
• "pde": Partial Differential Equations, or the PDE toolbox
• "optimset": the routine for setting up options for the ODE and optimization routines
• "pdepe": parabolic-elliptic PDEs in 1-D routine pdepe()
• "ode": Ordinary Differential Equations
• "differential equations": usually Ordinary Differential Equations

[Jan]

BVP: Boundary Value Problems, IVP: Initial Value Problems, DAE: Differential Algebraic Problems

Answer 9

[Walter Roberson]

Tags dealing with Optimization

• "optimization"
• "fmincon": function minimization with constraints routine fmincon()
• "fminbnd": function minimization with boundaries routine fminbnd()
• "minimization"
• "pso": particle swarm optimization
• "mopso": multi-objective particle swarm optimization
• "ga": indicates Genetical Algorithms in general, or the specific ga() routine
• "aco": ant-colony optimization
• "abc": artificial bee colony

Unresolved: "genetic algorithm" or "genetic algorithms", or use "ga" as the canonical form?

Unresolved: "linprog" versus "linear programming"

Answer 10

[Walter Roberson]

Tags dealing with Graphics

• "guide": indicates the Graphical User Interface DEsigner, GUIDE
• "handle graphics": indicates a Question about the operations of the MATLAB graphics subsystem
• "gui": indicates a Question about creating Graphical User Interfaces
• "uicontrol": indicates a Question about creating or using MATLAB's User Interface Controls
• "legend"
• "patch"
• "surf"
• "mesh"
• "plotyy"
• "colormap"
• "linkprop"
• "isosurface"
• "uitable"
• "slice"
• "scatter"
• "scatter3"
• "waitfor"
• "uiwait"

Unresolved: is "plot" specific to the plot() routine, or is it about plotting in general, or should that be "plotting" as a tag ?

Unresolved: "contour plot" or "contour plots" or "contour-plot" ?

[Walter Roberson]

Should we split this into plotting vs GUI ? plotting is a big subject.

[Jan]

"plot" is fine for all 2D graphics. For 3D graphics "plot3D" might be better than "mesh"/"patch"/"surf", because it covers "surface", "cylinder", "sphere" etc also. If a question really concerns a specific command like "surf", I'd use the command name as additional tag at all.

[Walter Roberson]

I would prefer to have some way to tell the difference between discussion of plotting, and discussion of the plot command. In the cases of "error" and "help" when referencing the command I tag complete with () afterwards, such as "error()", but I suspect there are too many people likely to use "plot" without "()" to make that usable. I think I would feel more comfortable with "plotting" as the category and "plot" for the command.

I keep in mind, though, the number of Questions that would have to be reviewed to impose consistency. Still, we can always come up with something that we apply going ahead, and only on any old postings that we feel like touching up.

Answer 11

[Walter Roberson]

Tags dealing with Image Processing

• "image processing": a general tag. As the category is quite large, usually a more specific tag should be used
• "image segmentation"
• "ocr": optical character recognition
• "lpr": license plate recognition
• "bwmorph"
• "bwlabel"
• "imnoise"
• "color segmentation"
• "image quality"

The tag "npr", meaning Number Plate Recognition, is sufficiently less common that it is not encouraged.

Unresolved: "optical character recognition" or should "ocr" be the canonical form?

[Ryan]

Possibly add a tag to handle medical image modalities such as CT/MRI/all the fuzzy and letter named (K,C) clustering segmentation methods?

[Walter Roberson]

I do not often see the modalities listed as tags. Though I do see dicom related tags. But please go ahead and propose.

The clustering techniques are used for other tasks as well, but as far as I am concerned it would be fine to list a tag under multiple groups.

Best spelling of "kmeans" vs "k-means" vs "k means" needs to be decided, partly by review of existing postings to see what people actually use now.

[Ryan]

My post was terribly unorganized (wrote it while running out of work).

I think k-means should be used. Dicom should be another tag, I know some occasional Answers browsers who that tag may be handy for. I missed the fuzzy tag being included with the uncategorized tag post.

Answer 12

[Walter Roberson]

Tags dealing with Robotics

• "arduino"

[Jan]

And "robotics" for non-arduino projects.

[Walter Roberson]

lego, mindstorm, and kin

Answer 13

[Walter Roberson]

Tags for Energy and Power

• "solar": includes photovoltaic cells, but also solar heating and other related topics
• "pv: indicates photo-voltaic cells
• "wind": includes wind turbines, but also other wind-related energy topics
• "load flow"
• "ieee bus", "ieee 5 bus", "ieee 6 bus", "ieee 7 bus", "ieee 14 bus", "ieee 30 bus", "ieee 34 bus", "ieee 57 bus", "ieee 300 bus", "ieee 1000 bus"
• "upfc": Unified Power Flow Controller
• "mppt": maximum power point tracking
• "igbt": Insulated Gate Bipolar Transistor

Unresolved: merge "load flow" and "load flow analysis" ?

Unresolved: "newton's method" or "newton raphson method"

Answer 14

[Walter Roberson]

Tags for Data Import and Export

• "xlswrite"
• "xlsread"
• "excel"
• "load"
• "save"
• "csvread"
• "dlmread"
• "data import"
• "importdata"
• "textscan"
• "textread"
• "uiimport"

Unresolved: "activex" or "activexserver"

[Jan]

"activex" will catch the "activexserver" questions also. What is "textread"?

[Walter Roberson]

"textread" is largely historical, but some of the users here still use very old versions.

Answer 15

[Sean de Wolski]

• "not a bug" For questions titled "Bug with ..." E.g. MATLAB bug (0.3 == 0.2+0.1)
• "poofing" When users want to "poof" variables like a magician with a rabbit in a hat.
• "which -all" For questions where the solution is removal of a shadowed function

Answer 16

[Walter Roberson]

Tags dealing with Symbolic Computing

• "sym"
• "syms"
• "subs"
• "mupad"
• "maple"

[Jan]

The distinction of "sym" and "syms" reduces the success of a search. I'd prefer "syms" and appending an "s" automatically to "sym".

[Walter Roberson]

The search engine automatically removes plural "s" from the search criteria, and from the text to be matched, so searching for "syms" is currently the same as searching for "sym" and either would find the other.

[Jan]

The search engine is smart with trailing s?! I failed last week using "tags: meta", because it must be "tag: meta". Brr.

[Walter Roberson]

I'm thinking of when the user searches without a prefix, e.g., search for sym would be the same as search for syms

Answer 17

[Walter Roberson]

Tags dealing with Data Analysis

• "pca": Principal Component Analysis

Unresolved: "principal component analysis" or "principal components analysis" or use "pca" as the canonical form?

Answer 18

[Walter Roberson]

Tags dealing with Neural Networks

• "nn": Neural Networks in general
• "anfis": Automated Neural Network Fuzzy Inference System
• "nntool"

Unresolved: "ann" or "nn"; "neural network" or "neural networks" or use "nn" as the canonical form?

Answer 19

[Walter Roberson]

Tags not yet categorized

• "fex": a reference to the Mathworks File Exchange, http://www.mathworks.com/matlabcentral/fileexchange/
• "nlfit": non-linear fitting routine nlfit()
• "fis": Fuzzy Inference System (fuzzy logic)
• "duplicate post requiring merging"
• "duplicate post"
• "java"
• "fortran"
• "mex"
• "perl"
• "vba"
• "speech recognition"
• "voice recognition"
• "hmm": Hidden Markov Models
• "mfcc": Mel-frequency cepstral coefficients
• "saveas"
• "print"
• "export_fig"
• "imwrite"
• "imread"
• "pwm": pulse-width modification
• "lsqnonneg": least squared fitting with non-negative parameters routine lsqnonneg()
• "humor" (rather than the more proper "humour")
• "beer"

Unresolved: "k-means" or "kmeans"?

[Jan]

"duplicate post requiring merging" and "duplicate post" should be caught by a flag. As soon as the duplicate post is deleted, the tags are meaningless.

[Walter Roberson]

There are bunch of old duplicates still in the system.

Also, "duplicate post requiring merging" usually implies that "someone" should move Answers or Comments to another Question, because the topic is active on multiple Questions. Sometimes, though, I do tag posts that way and leave them when there has been no response on the duplicate, as I sometimes get weary of doing the editing needed to merge the new phrasing into the old Question. I guess I could Close and include the URL of the duplicate in the closure message, but sometimes I do not feel like looking up the old URL. Especially if my connection to Answers is acting up like it was all last week.

Answer 20

[Walter Roberson]

Tags dealing with elements of the MATLAB Language

• "if statement"
• "for loop"
• "global"
• "function"
• "logical indexing"
• "nested functions"

Avoid "if loop", as there is no such thing in MATLAB.

Unresolved: "while" or "while loop" ? "matlab function" or "matlab functions"? "cell" or "cell array" or "cell arrays" ?

[Daniel Shub]

A tag related to memory allocation is also probably useful. Possibly preallocation, but I think the more interesting questions might be when you cannot preallocate.

Answer 21

[Walter Roberson]

Tags dealing with MATLAB data types

• "char"
• "uint8"
• "double"
• "strings"

Unresolved: "structure" or "structures"

[Jan]

"struct" for structures. Singular "string". "uint64" etc. "oop" for object oriented programming.

[Walter Roberson]

"struct" is the implementing call, but it is often more natural to discuss the topic, "structures"

People seem to find "strings" more natural to discuss than "string"; I do too.

Answer 22

[K E]

Tags dealing with Simulink

• "algebraic loop"
• "scope"
• "findvars"
• "set_param" and "get_param"
• "sim"
• "existing mdl" - Many Answers seek an existing model similar to the one that the author wants to build, and there are many example mdl files in the file exchange and documentation. I think it is legit (not doit4me) since Simulink is visual and thus lends itself to learning by example.

More experienced Simulink users can contribute additional tags, no doubt.

Answer 23

[Chad Greene]

• "pullingteeth": When the asker does not provide enough details for readers to answer the question, then only divulges small bits of information when asked for more details.

[Joseph Cheng]

Not exactly an antonym but "google-able" or equivalent tag should be applied where some questions could be solved by a 30 second search engine query (even within Matlab Answers).

Answer 24

[Robert Rasche]

Since when (and why) does Matlab Central remove underscores from the tags added via the Add-Tags button - it does for me in this moment at least.

I wanted to tag a file I have uploaded to the File Exchange with "find_system" and "get_param" and such, because my file relates to those Simulink model API functions and others. There are certainly entries on the platform right now, that have the same tags that i want to use, but i cannot add them now.

Is there another way to enter tags in verbetum to be added to an existing File Exchange entry?

I know, this might not be the correct place for this inquiry, however someone more involved in the platform might know where to channel this (it clearly isn't a Mathworks product feature, but rather an issue of this platform)

[Walter Roberson]

Thanks, I have asked Mathworks to review this. With Christimas so close it might be a bit of time before anyone looks.

[Image Analyst]

They're looking into it. I'd rather have them remove the hash marks from the tags of all those Twitter users.

[Manju Jonchhe]

We are investigating the issue with adding tags in File Exchange with the underscore. We will get the issue fixed soon. Sorry for the inconvenience.

[Robert Rasche]

Thank you for your help @Walter Roberson and @Image Analyst