Find in a cell array?

Question

M G 2013-8-7

7
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/84242-find-in-a-cell-array

评论： Marwan Malaeb 2022-5-20

采纳的回答： Jan

Hello all,

Suppose a cell array 10x1 consisted of random numbers from 1 to 5. How can I find the locations for number 5?

All the best,

MhD

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Elias Berra 2015-11-17

X = my_array_data [row,col] = find(X==21) %In this example, it retrieves the cell location which contains the value 21.

Marwan Malaeb 2022-5-20

call this array for example X

type k=find(X==5)

it will return for you the number of the cell that has the value of 5.

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Answer 1

Jan 2013-8-7

77
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/84242-find-in-a-cell-array#answer_93817

编辑：Jan 2013-8-7

在 MATLAB Online 中打开

C = {1,5,3,4,2,3,4,5,2,1};
index = find([C{:}] == 5);

Here [C{:}] is a faster inlined version of cell2mat.

Alternative:

index = cellfun(@(x) x==5, C, 'UniformOutput', 1);

Or the long and most likely faster form:

index = false(1, numel(C))
for k = 1:numel(C)
  index(k) = (C{k} == 5);
end

[EDITED] If you are talking of a cell string, this is much faster:

D = {'1' '5' '3' '4' '2' '3' '4' '5' '2' '1'};
index = find(strcmp(D, '5'));

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Jan 2013-8-8

在 MATLAB Online 中打开

This looks strange. When eheader is numerical, converting it elementwise inside a cellfun call to a string and afterwards by char to a char matrix is cruel. Then assuming a certain number of spaces around the value is fragile, because the width depends on the values. What about this (I cannot open the posted MAT file, better post code in the forum which creates the example data):

x = find([eheader{:}] == -88)

STRCMP works much faster with cell strings, so at least do not let CHAR() create a CHAR-matrix.

Kylie Hansen 2017-8-16

Just a casual MATLAB coder dropping by this older thread on a hunt for answers. Your response for the cell string method worked easily for me. Thank you so much for including it!

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Answer 2

Bill Tubbs 2022-2-15

6
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https://ww2.mathworks.cn/matlabcentral/answers/84242-find-in-a-cell-array#answer_896925

在 MATLAB Online 中打开

Just in case someone comes here looking to do this with a cell array of chars as I was, it's quite easy this way:

my_cell_array = {'a', 'b', 'c'};
i = find(strcmp(my_cell_array, 'b'));
assert(i == 2)

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hongyi xu 2022-4-17

Genius! Your supplement exactly fits my question.

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Answer 3

Caroline 2013-8-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/84242-find-in-a-cell-array#answer_93816

编辑：Azzi Abdelmalek 2013-8-7

在 MATLAB Online 中打开

cellarray_new = zeros; %initializing the array 
ind = 1; %indices for new array
for j = 1:10
  if (cellarray(j) == 5)
      cellarray_new(ind) = j;
      ind = ind + 1;
  end
end