When you have different values assigned to different strings, how can you use these values in a loop?

I want to make a loop and do a few things inside this loop, but none of them work yet. Part of it has to concern with months, for the example I will just use january and february:

jan = 1:31;
feb = 32:59;

First I want to make an empty matrix to fill later:

jan_mat = nan(length(jan),10)

Important is that I want to have a name including jan so I can easily find it back later. Another important thing is that I need the value of the length of jan. This formula works, but I want to have it in a loop so I don't have to define it for every month seperately.

What I tried:

B = {'jan','feb'}

This gives

B(1) = 'jan'

and

B{1} = jan.

I thought 'I need the second' so I define

C{i} = [B{i} '_mat']

This seems to work and gives

C(1) = 'jan_mat'

and

C{1} = jan_mat

I would think I could just write:

for i=1:2
           C{i} = [B{i} '_mat']
           C{i} = nan(length(B{i}),10)
end

But this fails to work. Can anybody explain how I can get what I want?

Answer 1

[Adam]

Use a struct to hold all the months and something like the following:

months = { 'jan', 'feb',...'dec' }

monthDays.jan = 1:31;
monthDays.feb = 32:59;
% etc

for i = 1:numel( months )
   monthVals.( months{i} ) = nan( numel( monthDays.( months{i} ) ), 10 );
end

There are almost certainly better ways to create the month days that just 12 lines of hard-coding the numbers like that, but that part is a 1-time constant setup so not really important. The key is that you can use dynamic field names far more easily than dynamic variable names (and it keeps your workspace tidy by grouping them in a single struct or 2 structs in this case).

[Evelyn]

Thanks, that is very helpful!