Comparing characters in a matrix

I have a (nx1) matrix,M, that stores a list of characters and I need to iterate through a loop and keep comparing the i-th character in the matrix with a temp character.

But I'm not sure how to do this, i tried using M{i,1}== tmp and strcmp(M{i,1},tmp) but neither seem to work. Please help, thank you so much!

[TAB]

Please explain with the help of example of data and your expected output.

[Mini]

M =

    'U'
    'C'
    'Y'
    'H'
    'O'

tmp = 'U'

I want to increment the variable 'count' every time a character in M matches that in tmp.

[Matt J]

In what you've shown, M is a cell array of strings, not a matrix. If M is always nx1, it would indeed make more sense to convert it to a matrix and maintain it that way

 M=[M{:}].'

[Mini]

    cmd = ['tesseract ',file,' tmp -psm 10']; %this is a command to run OCR and will save the character returned in a tmp.txt file
    system(cmd);

    %save temp results
    f2 = fopen('tmp.txt','r');
    tmp = fgets(f2); %this is the tmp character I want to compare against

    if strcmp(M(i),tmp)
        count = count+1;
    end;  if true
    % code
  end

[Mini]

oh dear I realised my mistake... its not working because the characters in M are stored with the apostrophes in the format: 'U','C','Y'... but in the variable tmp, the character are just stored as: U, C, Y... is there a way to solve this kind of problem?

Answer 1

[Azzi Abdelmalek]

strcmp(M(i),tmp)

[Mini]

doesn't workk :(

[Matt J]

Azzi's code will work fine if M is truly a matrix as you claim. The following example below proves this

>> M=['UCYHO'].'; tmp='U';
>> strcmp(M(1),'U')

ans =

       1

I again suspect, however, that M is a cell array and that you do not understand the difference between cell arrays and matrices.

[Mini]

Hey, I tried using 'U' instead of tmp and stepped through the code and figured that it works that way... the problem is because the character in tmp does not have the apostrophe so its just U instead of 'U'. Do you know how to solve this?

[Azzi Abdelmalek]

Mini, to make it simple, give a sample of M, and tmp, and type

whos tmp
whos M

and tell us what you've got

[Mini]

M(1) = 'U' tmp = U

thats why strcmp(M(1),tmp) returns false, but when I try strcmp(M(1),'U') it returns true.

[Azzi Abdelmalek]

Type

whos tmp
whos M

and tell what you've got

[Mini]

>> whos tmp

Name Size Bytes Class Attributes

tmp 1x2 4 char

>> whos M

Name Size Bytes Class Attributes

M 257x1 15936 cell

[Azzi Abdelmalek]

The problem is tmp is not equal to 'U' but to something like

   'U           '    % with spaces

Try this to remove space from tmp

strcmp(M(1),strtrim(tmp))

[Mini]

omg this works, thank you sooooooooo much!!! (: Hope you have a great week ahead!! (:

Answer 2

[Matt J]

 count=sum([M{:}]==tmp)

[Mini]

but M is a matrix, and i need to access only one index at a time to compare against tmp

[Matt J]

But your code shows that all you're doing is counting occurrences of tmp. That's also what you stated earlier that you wanted to do

I want to increment the variable 'count' every time a character in M matches that in tmp.

If this is all you are doing, then my code does that for you in one line. If M really is a matrix and not a cell array, then my proposal would simplify to

 count=sum(M==tmp)

However, your example clearly shows M to be a cell array.

[Mini]

oh thank you for the explanation... now i understand where you are coming from.. but this tmp changes value in every iteration, so in that case I will have to check it in every iteration right?

[Matt J]

Not if there's a vectorized way of creating tmp. If M and tmp are string vectors of the same length, you can still do

count=sum(M==tmp)