Matlab find string within cell array

Question

I have a cell array (n-by-1 dimension) containing both strings and cells, which looks something like this

{
{'r1'}     % -> cell content is in format 'char'
{'r2'}     % -> cell content is in format 'char'
{1x2 cell} % -> cell content is a cell array: [{'r1'}{'r2'}]
{'r3'}     % -> cell content is in format 'char'
{1x2 cell} % -> cell content is a cell array: [{'r1'}{'r3'}]
{1x2 cell} % -> cell content is a cell array: [{'r2'}{'r3'}]
{1x3 cell} % -> cell content is a cell array: [{'r1'}{'r2'}{'r3'}]
...
}

I need to find the row-index where the some string is included, e.g. 'r2'. I usually use strfind for this purpose which works great if the cell array has a consistent format (hence 'char'-format within each cell).

Is there any way to apply this function to the cell array structure which is displayed above?

Thanks!

EDIT: Please find attached three images showing the data structure that I am using, since I am not sure how to exactly show/explain the hierarchies and layers of the cell array in text. Hope that helps. Also find attached the outcome of the code.

Code used:

change = 'r1.m';
srch = cellfun(@(x) strfind(x, change), strats, 'UniformOutput', false);
stringInRow = cellfun(@(x) numel(x) == 1 || (numel(x)>1)*numel(cell2mat(x))>0, srch);
rows = find(stringInRow);

dfrib · Accepted Answer · 2016-03-10 11:23:59Z

3

You could use two subsequent cellfun calls: one to perform the string search (cell by cell), and one to evaluate it (found string true or not false?)

%// example data
c{1} = 'r1';     
c{2} = 'r2';    
c{3}{1} = 'r1'; c{3}{2} = 'r2';
c{4} = 'r3';
c{5}{1} = 'r1'; c{5}{2} = 'r3';

%// example search
searchForString = 'r2';
srch = cellfun(@(x) strfind(x, searchForString), c, 'UniformOutput', false);
stringInRow = ...
  cellfun(@(x) numel(x) == 1 || (numel(x)>1)*numel(cell2mat(x))>0, srch);
               %// ^-. short-circuit scalars here     ^
               %//                                    |
               %// since cell2mat is valid only for cells or empty arrays

With resulting stringInRow:

stringInRow =

     0     1     1     0     0

If you want to explicitly list the rows, you can just make use of find on the stringInRow boolean vector

>> foundStringInRows = find(stringInRow)

foundStringInRows =

     2     3

answered Mar 10, 2016 at 11:23

dfrib

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12 Comments

Mikhail_Sam Over a year ago

a little mistake: looks like you mean use c{3}{2} second time instead of c{5}{2}. Can you clarify please, why searching in this cell array returns this answer? As I can see it mast be 0 1 1 0 0 because c{2}='r2' and c{3}{2} = 'r2'. So why it is 0 1 0 0 1?

dfrib Over a year ago

I guess I beat you to fixing my own mistake (within 5 minutes also :) ) just prior to your comment. With this fix, search returns 0 1 1 0 0, as it should. Good catch though!

Mikhail_Sam Over a year ago

ahh, really! I have had to refresh it first! You are too fast ;D

Benvaulter Over a year ago

thanks for the quick reply! The example works perfectly and does what I would like to achieve. However, when I apply it to my data and does not produce the correct results. The problem appears to be that when I produce search, all cells will contain another cell array (of different sizes). Any idea why this would happen?

dfrib Over a year ago

@Benvaulter Are you sure that your data is a cell array, and not a single cell containing a cell array? If the latter, start by extracting the actual cell array (e.g. cArr = c{1}). If this is not the issue, please show us a fully verifiable example how (a subset) of your data looks like.

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