How can I quickly find the difference in function usage between different MATLAB versions? For example, the Name-Value Arguments "QuoteStrings" of the function writetable

On the version of MATLAB 2021b, the following code is correct:

 writetable(mytable,'result.csv','Delimiter',',','QuoteStrings',0)

However, the same code cannot run on my friend's computer. The version of MATLAB on his computer is 2022b.

From the official help document, we can see that the name value parameter "QuoteStrings" has modified the value parameter.

Previous version：

% 'QuoteStrings' A logical value that specifies whether to write

% text out enclosed in double quotes ("..."). If

% 'QuoteStrings' is true, any double quote characters that

% appear as part of a text variable are replaced by two

% double quote characters.

Latest version：

% "QuoteStrings" - A flag which specifies when to quote output text.

% - "minimal" (default) Any variables which contain

% the delimiter, line ending, or the double-quote

% character '"' will be quoted.

% - "all" All text, categorical, datetime, or

% duration variables will be quoted.

% - "none" No variables will be quoted.

Therefore, in order to avoid differences between different MATLAB versions, I can only change the code to:

 try
    writetable(mytable,'result.csv','Delimiter',',','QuoteStrings',0)
 catch
     writetable(mytable,'result.csv','Delimiter',',','QuoteStrings','none')
 end

Similar situations are often encountered in many other functions. Many name-value parameters may be proposed in a newer version, but the MATLAB official website does not provide relevant compatibility suggestions.

For example, the 'CData' parameter in the bar function will report an error in MATLAB2017a.

So, what's a good way to quickly know the modification of a function? I hope you can give some good suggestions or share your experience. Thank you.

Answer 1

[Rik]

A few releases ago Mathworks introduced a changes section at the bottom of the documentation page. Other than that, it is simply a case of comparing documentation pages.

There is no standard way. There is a reason I keep my ifversion function on the file exchange up to date. Instead of try catch blocks (which can get messy, especially with multiple options), I use ifversion to branch my code. That way any errors will keep making sense (your code can throw an error about the parameters if there is a file access error on releases where you need the version in the try section).

Edit so it doesn't get lost (thanks Steven, I will try to remember to suggest them in on the FEX description page):

If you don't want to include ifversion in your code, you can probably use either verLessThan (introduced in release R2007a) or isMATLABReleaseOlderThan (introduced in release R2020b).

[qqffssxx]

Thanks for sharing your tools ifversion .

For example, the Name-Value Arguments "QuoteStrings" of the function writetable，Just now I have carefully checked again, and the MATLAB official website does not explain the modification of this parameter.

How to find the difference between different versions of a function is very important. Using the writetable function as an example, I don't know if you have a good method.

[Rik]

There is a feedback box at the bottom of the documentation page. In my humble opinion this is a change that should have been mentioned in the release notes and/or the documentation page itself.

In terms of your specific code, I would suggest this:

if ifversion('<','R2022a') % this behavior changed starting in R2022a
    QuoteStrings = 0;
else
    QuoteStrings = 'none';
end
writetable(mytable,'result.csv','Delimiter',',','QuoteStrings',QuoteStrings)

[qqffssxx]

The most difficult point is how to know which version of this function began to change. Take our example, how do we get the change of MATLAB R2022a, which is not introduced in the description of this function on the MATLAB official website.

[Walter Roberson]

What you are asking for does not (consistently) exist. Some changes have started to be listed, but some of the toolboxes do not appear to have any of those notes at all, and when the notes started varies a lot. All you can do is look at the Release Notes and hope that the change was mentioned.

Change histories are definitely useful... they just don't exist, for the most part. And there are tens of thousands of functions so it is beyond the resources of any volunteer to put together a list.

[Rik]

I only do this case by case. I just looked up in which release this behavior changed by reading the documentation of the release in between.

I personally create tester functions to test behavior of my function. If and when something goes wrong, I try intermediate releases. I use the release notes to see the big changes, but I don't rely on them to find these things.

[Steven Lord]

You could use verLessThan (introduced in release R2007a) or isMATLABReleaseOlderThan (introduced in release R2020b) to check if the release of MATLAB you're using is too old or new to have a particular function or piece of functionality, assuming you only need to check back to release R2007a or release R2020b respectively. This could avoid users to whom you provide your code needing to install ifversion from the File Exchange.

[qqffssxx]

Thank you, it's helpful.