Write a forum post that can be answered

In the growing world of free open-source software (FOSS) support often comes from online user forums. The quality of those forums can vary in terms of how many people reply to questions but, even in the best of them, a poorly phrased query will not be answered.

I spend a lot of time answering questions on the PsychoPy users forum where users of the PsychoPy stimulus presentation package can get and give help on how to create and improve their experiments. That forum is very active and a lot of people are willing to answer questions.

So why, you might ask, did your question not get an answer? Well, it might be that the timing was bad and everyone was busy, or that you had a great question but nobody knows the answer, but here are some tips to giving your question the best chance of being answered.

The key is that the people answering questions are doing so in their spare time. Most open source software is free and supported by volunteers with day jobs; that's why the software you downloaded was free. Those volunteers are generally willing to answer a question that will only take a few minutes to write. You need to make it easy for them. You need to write something that can be answered and preferably in a short email. Here are some examples of posts that cannot be answered and will typically lead to your question being ignored:

• I want to use your software but I don't know how. Could somebody give me a working version of what I need? Presumably this will take more than 2 minutes so, unless the software only has 10 users, the answer is "No, it isn't possible for us to create it for you".
• I created a script but it doesn't work. Any ideas? Could you give us a clue? If I ask you "Why is there no image on my TV?" you wouldn't be able to help me. There are too many possible options. What do you mean by "doesn't work"? What have you tried and what happened (for each option you tried)?

Following your message with "I'm really desperate, can't somebody help me?!! PLEASE?!!!" doesn't help your case. If I can't answer your question then I can't answer your desperate question either.

So, if some questions are not going to get an answer, how do you write a post that will? Partly you need to know how to troubleshoot the software and your script.

Know the basics and use Google first

If you can't use the basic functions of the software yet then you need to start with the documentation or go on a training course. For PsychoPy see the PsychoPy training resouces page. It's fine to announce that you're a "newbie" but implicitly announcing that you haven't looked at the documentation yet will get you ignored.

A huge number of questions have been answered before, and Google is pretty good at finding the previous answers. In particular, you could try using the error message that appeared in your Google search, but simple text of what you aimed to do might work too. Google really is amazing.

Expand on "it doesn't work"

The phrase "it doesn't work" almost never gives enough information. Check your email for that phrase and replace all instances with something more informative. 

What happens when it doesn't work? Does the software crash? Is there an error message? (For PsychoPy) does the stimulus simply not show up? Some people will write "I've tried 4 different ways and none of them worked" but that still doesn't help. What happened for each one?

Explain what is different about your case compared to most others

If you're using software that is popular then in most cases it must be working. If it isn't working in your case then you should think a little about what might be different. Do you have any unusual computer hardware (e.g. a display that's unusually large)? Is the operating system set up in a different way (e.g. you use Urdu whereas most users are using American)?

Does the software provide demos and if so do they work? If none of them work then we could rule out your own coding as the problem. If some of them work then we can narrow down the problem. If they mostly do work then maybe the problem is with your own script.

Are there things that you are doing that are particularly unusual? Are you adding custom code? Are you trying to get unusually short durations for something? Quite often a post on the PsychoPy forum will say that "PsychoPy freezes when I present text" and after several iterations it turns out that the user had written their own custom code for presenting text that used a never-ending loop. Is it possible that your code was the problem, rather than the software?

Anything that you customized needs explaining and probably needs you to paste the precise details (e.g. code).

Don't write too much irrelevant detail

Although you need to provide enough detail for your query to be answered, if you write a really long post with a lot of irrelevant detail, or if you provide your entire 900-line script, nobody will have time to read the post at all.

So, the key is how to give enough detail that it can be answered, and not so much that it will be ignored. What counts as important will differ from one package to the next. For PsychoPy the following are nearly always important:

• are you using code or Builder to create your study?
• what version of PsychoPy do you have installed (and have you customised that in any way?)
• what operating system?

The best way to give just enough, but not too much, detail is to give a minimal working example of the problem. That, ultimately is the aim, but that might warrant a separate blog post.

Just to reiterate, following this advice doesn't mean your question will absolutely get answered. I've seen perfectly good questions go unanswered on the PsychoPy list, often because I (and presumably others) just did not know the answer, or it was going to take a while to work out (sorry!) but the tips above will give you the best chance.

Python versus Matlab for neuroscience/psychology

A lot of people ask me why I use Python instead of Matlab, or which is easier/better to learn. Maybe it's time I provided a comparison for psychology/neuroscience types to decide which language is better for them. Note that, although I write a prominent python package, this article is not aimed at trying to convert you. If Matlab works for you and makes you happy that's great! Personally, when I switched to Python I never looked back, and this explains a little about why.

Overall

Overall Python is a more flexible language and easier to read, and for me those two things are really important. Many people don't care whether their code is readable or clear for the future. They want it just to work now. For me, being able to understand the code again in a year's time is really important, and learning a new language wasn't too hard.

A lot of the differences between Matlab and Python come down to two things: 

1. Matlab has a commercial, proprietary development model whereas Python is open-source. I won't go into that aspect much in this post. Some time I'll write a separate post about why I personally prefer the open-source model (they each have their benefits).
2. Matlab was designed to do maths but can be used more generally. Python was designed to be general but can be used for maths. That alters the way the languages work and the nature of the other users. That's also part of the reason that Python ships as part of Mac OS X and most Linux distributions. It's so generally useful it's made a part of the operating system.

Price and support

Price was certainly a part of my original decision to switch to Python. I was sick of setting up licenses, or getting blocked because the license server had too many users. Or needing to distribute processing to other machines, and discovering that they didn't all have the necessary (paid-for) toolboxes. But if it were just about the licensing I would have switched to Octave, a free alternative with almost identical syntax. The bigger issue I had was that I didn't actually like the language that much. Too many of the things that I felt should be core components of a language were bolt-on afterthoughts in Matlab.

Also at that point in time (2002-3) Mathworks was unsure if it would continue to support Apple Mac. I wanted to be able to choose what platform I used and not have that determined for me by Mathworks.

Generality

Ultimately there's little that Python can do that Matlab can't, and the converse is even more true. So why should it matter what they were originally designed for? Well, it does alter the decisions made by the programmers that built the systems. Matlab was designed to do maths and was extended to do much more; it was designed to be used by regular scientists not by programmers. Python was designed as a general language, that cold also do maths. On the whole that means that Matlab scripts/packages work very well for moderately complex tasks but they don't scale up very easily. Python might take a little more effort to get going, but saves you headaches in the long run.

Concrete examples? OK, just a couple.

1. How often in Matlab have you had some error message that made no sense that turned out to be caused by two functions on your path having the same name, or because you'd assigned a variable to the name of a function, and now that function doesn't work? Matlab assumes that everything on your path should be available at all times, because the developers didn't expect people to have hundreds of thousands of different functions on their path. Fair enough; if you only have 500 functions then giving each one a unique name is reasonable. Python is designed to have much larger numbers of libraries and functions installed, and the idea that each should need a unique name is quickly unworkable. So it becomes important that the entire path isn't constantly available in the 'namespace'. So in Python, like most other programming languages, you need to manually import the libraries that you want to use. That means a couple of extra lines at the start of your script but it also means you stand a better chance of avoiding name conflicts despite having a huge number of available functions in your libraries.
2. Python was designed from the ground-up to support object-oriented programming, with inheritance and dynamic updating of classes. For someone with experience in programming those things are incredibly useful allowing greater re-use of code and fewer bugs in large programs. For doing maths, object oriented programming seems less important and so the concept was rather late to appear in Matlab and the fact that it was bolted on as an afterthought shows.

Powerful syntax

I don't think there's any question that Python's syntax is superior to Matlab's. Some aspects might take you some getting used to (e.g. the fact that indices start at zero, or that correct indentation is a requirement). But in the end it has a huge number of features. Here a just a couple to give you the idea.

Fantastic string handling. Imagine being able to do things like this in Matlab:

>>> a='hello'
>>> b=' world'
>>> a+b #combine two strings? just add them!
'hello world'
>>> (a+b).title() #title is a method of all string objects
'Hello World'
>>> a==b #why would you want to write strcmp?!
False
>>> a>b
True
>>> str1="Strings can be surrounded by single or double quotes"
>>> str2='"Wow" and I can include the other type in the string?!'

(For other string-handling possibilities see the python tutorial).

How about the fact that arguments to functions can be called by name rather than by location in the argument list? So if you only want the 1st and 8th argument just use their names and the other args will take the default values. Sweet! To see this in action see http://docs.python.org/tutorial/controlflow.html#keyword-arguments

Many things are easy in Python and considerably less readable in Matlab. Maybe they aren't important to you, but when you have very large scripts they can become a huge time-saver.

Available libraries

Although in science there are lots of Matlab users, which is great for sharing a script. What many people don't realise is that, overall, Python has many more users. So when you need help with, say, sound handling or importing some new file format, you are much more likely to find a ready-made library available for Python. That was another reason for me originally switching to Python; in early 2003 it already had a fully functional wrapper for OpenGL so I could use hardware-accelerated graphics directly from my scripts.

When I decided to build an editor and experiment builder GUI for PsychoPy I could do it all within Python, with relatively little effort, from existing Python libraries (e.g. wxPython). I can't imagine doing all that Matlab (although much of it would be technically possible it would be extremely painful).

When Microsoft changed the format of Excel files, soon enough there was a Python library (openpyxl) to read and write them, because an enthusiast went and created it. On Matlab, you still can't do that with a Mac, because Mathworks hasn't yet made that added it.

Ultimately

It is because of Python that I was able to write PsychoPy, and it's why other programmers have jumped on board the project. The clean easy syntax and the huge huge array of libraries allow normal people to write pretty professional applications.

An online repository for sharing experiments?

Have you ever read a psychology/neuroscience journal article and wondered if the information the authors had given you in the methods section was really sufficient for you to replicate the study?

Have you ever wanted to start a study with a new piece of software or something outside your normal method, and wished there was some existing experiment code that you could adapt for your needs?

A couple of people on the PsychoPy users list have suggested that it would be good to have a place to upload experimental code and materials to share.

It would serve a few purposes:

• makes a study genuinely replicable, because you would be able to fetch the actual experiment as the authors used. 
• publicises an experiment that you've run because people could browse the repository looking for experiments they found interesting
• provides a starting point for new users of a piece of software to build an experiment

The first goal can actually also be met by uploading your experiment to your own lab web pages, but that solution doesn't address the second and third points.

The repository would be agnostic to the subject of the study, and to the software used to run it. You would upload all the materials needed to run it (code, image files etc), tag which software package it was written for (PsychoPy, E-Prime, Presentation, Psychtoolbox etc...), provide a summary of what results should be expected and a reference to the paper showing the original (if published). Then you provide keywords about the topic that the experiment addresses so that people can browse or search for the experiment. Users might search by topic, keyword or software package to find experiments to learn from or replicate.

Potential issues

A few people have raised concerns about the idea:

• Will it lead people to run studies that they didn't actually understand? For example, see this post on eagle-eyed-autism describing a study going badly wrong because the authors had borrowed code and hadn't really understood it. Is the answer to make sure it's very difficult to run studies, so that the scientist has to really know what you're doing in order to manage? That seems more than a little arrogant.
• Will errors in studies propagate more? If a study has an error, when another lab writes it from scratch the error will likely not be made, but if they borrow and tweak the bug could propagate. I think the benefit that more eyes potentially examine the experiment and reduce the propagation of bugs.
• Why should someone else simply take the experiment that I spent hours writing? To me this one just seems blatantly at odds with the aims and philosophy of science. But I guess some people will feel territorial like that.
• People would never use such a site (unless forced) because they will be too embarrassed by the quality of their code, which was, after all designed to work without necessarily being elegant. I'm fairly sympathetic to this (although I've obviously shared many thousands of lines of my own code). But some people will be brave enough to expose their work fully, especially if it was generated by something like E-Prime or PsychoPy Builder, where the need actually to write code is reduced.

The idea is definitely growing on me, although I don't currently have the time to build the site, nor the funding to pay someone to build it.

I'm keen to hear more views. So feel free to comment below. Hopefully the idea will also be discussed as part of a satellite event on open-science at the Vision Sciences Society conference this May.