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Find index of cells containing my string

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New
New il 25 Feb 2011
Commentato: Cris LaPierre il 13 Gen 2022
Hi, I have a cell aray (40,000X1)in which every cell contains a string. I would like to find the indexes of the cells containing a specific string.
I used the following:
Index = strfind(Mycellarray, 'Bla');
I get the following error: ??? Error using ==> cell.strfind at 35 If any of the input arguments are cell arrays, the first must be a cell array of strings and the second must be a character array.
What is wrong, in the help file strfind accepts cell arrays and a pattern...?
Thank you
  7 Commenti
Yusuf Arslan
Yusuf Arslan il 26 Set 2017
Hello, I have got a similar Problem.
- find(strcmp(rawdata,'ggiBoundaries1(1,1)'))
I want to find in rawdata the first entry of ggiBoundaries1. But it doesn't work. The error message is =
"0×1 empty double column vector".
When I enter "ggiBoundaries1(1,1)" the output is a char. Maybe that's the problem or not?
Jan
Jan il 26 Set 2017
This is not an error message. It simply tells you, that the string is not found.
Are you really looking for the string 'ggiBoundaries1(1,1)' ? Or do you mean:
find(strcmp(rawdata, ggiBoundaries1(1,1)))
to search for occurrences of the first character of the variable ggiBoundaries1?
Please do not append a new question to an existing thread. Better open a new one. Thanks.

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Risposta accettata

Jan
Jan il 25 Feb 2011
Modificato: MathWorks Support Team il 23 Mar 2021
Do you want to search for 'bla' within the text in each element of the cell array, or for elements that are 'bla' exactly? If you explain this detail, then your question would be easier to answer.
If you are searching for text that has 'bla' as part of the text, then starting in R2016b you can use the “contains” function, as Alexander Cranney pointed out.
Index = find(contains(C,'bla'));
The function "contains" returns a logical array. This type of logical indexing can be used to make many workflows more efficient. For more on using logical arrays, refer to the documentation:
In previous versions of MATLAB (before R2016b), you can use the “strfind” function. However, “strfind” returns a cell array of indices. For any input cell whose text does not contain 'bla', “strfind” returns an empty cell. Use “isempty” and “cellfun” with the “find” function to find the empty cells.
IndexC = strfind(C,'bla');
Index = find(not(cellfun('isempty',IndexC)))
If you are searching for text that is exactly 'bla', then see Jos’ answer.
  10 Commenti
Aditi Bishnoi
Aditi Bishnoi il 22 Gen 2021
what to use if I want to find the exact string match 'bla'.
My cell array has both 'bla' and 'blah' elements, but i want to pick out only 'bla'.
Walter Roberson
Walter Roberson il 22 Gen 2021
Modificato: Walter Roberson il 22 Gen 2021
exact_match_mask = strcmp(YourCell, 'bla')
exact_match_locations = find(exact_match_mask)
provided that your cell entries are all character vectors.

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Più risposte (7)

Jay
Jay il 28 Mag 2016
Modificato: Jay il 28 Mag 2016
This worked for me:
idx = find(ismember(C, 'bla'))
  8 Commenti
per isakson
per isakson il 22 Mag 2020
It works as documented.
Matlab uses column-major order. (I fail to find a page to link to in the documentation.)
Try
%%
C = { {'a'}, {'b'}, {'c'}, {'a'}, {'a'}
{'b'}, {'a'}, {'c'}, {'a'}, {'c'} };
%%
cac = [C{:}]
idx = find(strcmp( cac, 'a' ))
%%
C1 = permute( C, [2,1] ); % switch rows and columns
idx = find(strcmp( [C1{:}], 'a' ))
it outputs
cac =
1×10 cell array
Columns 1 through 8
{'a'} {'b'} {'b'} {'a'} {'c'} {'c'} {'a'} {'a'}
Columns 9 through 10
{'a'} {'c'}
idx =
1 4 7 8 9
idx =
1 4 5 7 9

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Jos (10584)
Jos (10584) il 25 Feb 2011
So, your original array was a cell array of cells with a single string. Use STRCMP and FIND to get the indices of the cells with a cell containing the specified string
C = { {'a'}, {'b'}, {'c'}, {'a'}, {'a'} } % data
idx = find(strcmp([C{:}], 'a')) % single line engine

Matt B
Matt B il 14 Nov 2013
I realize this question is old now, but a simple way of doing this is to define an inline function:
cellfind = @(string)(@(cell_contents)(strcmp(string,cell_contents)));
You can then use this with cellfun to return a boolean value for each element of the cell. For example:
cell_array={1,eye(2),true,'foo',10};
string='foo'
logical_cells = cellfun(cellfind('foo'),cell_array)
logical_cells =
[0,0,0,1,0]
  3 Commenti
josh gore
josh gore il 26 Gen 2017
The inline function was a life saver!
Jan
Jan il 6 Giu 2019
@Matt B: strcmp accepts a cell array directly, so you can avoid the complicated cellfun approach with the expensive anonymous function:
cell_array = {1,eye(2),true,'foo',10}
strcmp(cell_array, 'foo')
>> [0,0,0,1,0]

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Omer Moussaffi
Omer Moussaffi il 26 Feb 2017
Faster options: count startsWith endsWith
E,g, Index = count(Mycellarray, 'Bla');

Jan
Jan il 25 Feb 2011
You can check if your cell is a cell string:
iscellstr(Mycellarray);
This displays the indices and contents of the non-strings:
Index = find(~cellfun('isclass', Mycellarray, 'char'))
disp(Mycellarray(Index));
Another idea is, that some strings are multi-row CHAR matrices:
Index = find(cellfun('size', Mycellarray, 1) > 1)

Peter Farkas
Peter Farkas il 9 Mag 2016
You can also explicitelly define the index matrix:
[rw, ~] = size(cellArray);
ind = [1:1:rw];
idx = strcmp(cellArray, stringToSearchFor);
yourResult = ind(idx);
It is kind of verbose, if you review the code in 2 years time, you will still know what is going on.

Mukesh Jadhav
Mukesh Jadhav il 9 Ott 2016
Modificato: per isakson il 10 Gen 2017
Haven't tested but this should work fine.
word_to_find=strfind(strarray,'stringtofind');
starray.index(word_to_find);

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