Replace cell contents using an if statement nested inside a for loop?

Question

Owen Gray 2021-3-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/765526-replace-cell-contents-using-an-if-statement-nested-inside-a-for-loop

评论： Stephen23 2021-3-7

I'm trying to run this change the contents of an 81698x10 cell array 'A'

[sizeA,rows] = size(A);
clear rows 
for n = 1:sizeA
    if A{n,8} == 'simulated' && A{n,4} == 1
        A{n,9} = A{n,9} + 60;
    end
end 

however when I try and run I get an error message-

Matrix dimensions must agree

Would greatly appreciate help with this! Thanks

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2021-3-7

在 MATLAB Online 中打开

Do not use == to compare strings, instead use strcmp or strcmpi. Replace

A{n,8} == 'simulated' % element-wise, unlikely to be useful for your situation.

with

strcmp(A{n,8},'simulated') % does what you want.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2021-3-7

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/765526-replace-cell-contents-using-an-if-statement-nested-inside-a-for-loop#answer_641351

在 MATLAB Online 中打开

sizeA = size(A, 1);
for n = 1:sizeA
  if strcmp(A{n,8}, 'simulated') && A{n,4} == 1
      A{n,9} = A{n,9} + 60;
  end
end

Reminder though that comparing character vectors is more expensive than comparing numbers so it might make sense to compare the number first.

A tip is that when you are using the && operator, that it can make sense to put the comparisons most likely to be false first, to fail with as little average work as practical. Likewise when using it can make sense to put the likely truths first to succeed with as little average work as possible. However, over the lifetime of a program, it is usually better to write clear code rather than worrying too much about optimization.