How do I write to a map of matrices?

So I am using the Map Container in MATLAB to store a matrix for keys of a specific character. The first thing I do is create the mappings and allocate space by doing:

for i=1:uniqueTimeStampsCount
   M(char(uniqueTimeStamps(i)))=zeros(uint8(max(y)+1),uint8(max(x)+1));
end

This part works fine as uniqueTimeStamps is just an array of numbers that I convert to chars. So for instance M('1') would map to a matrix of all zeros.

My issue is the next part where I want to go through a list of keys to access and modify the contents of the respective matrices:

for i=1:size(TimeStamp,1)
   temp = M(char(TimeStamp(i)));
   temp(y(i)+1,x(i)+1)= polarity(i);
   M(char(TimeStamp(i))) = temp;
end

The first part of this works where I store the value into temp and modify a specific (x,y) coordinate in that matrices. The issue is writing back to the map container. I am not sure why the line M(char(TimeStamp(i))) = temp; is not updating the mapping with the temp matrix.

Any advice is greatly appreciated.

Answer 1

[John Alexiades]

I figured out what my issue was. I was looking at the wrong key. When I do M(char(uniqueTimeStamps(i))), it did not mean M('1') but rather M(''). Everything works now.