MATLAB: Searching cell arrays

cell arrays

I want to find the index of a cell array that contains a specific string, but the search and find functions don't take cell arrays as arguments. How do I return the cell number that contains the string?

Best Answer

Should the cell exactly match the specific string? If so then use ismember().

Should the cell member start with the specific string? If so then cellfun() and strncmp()

Should the cell member contain the specific string as a substring somewhere in it? If so then cellfun() and strfind() and isempty()

The matching process on a cellstr can also be done by regexp(); you might need to cellfun() isempty() to determine the logical result for each entry. It is, though, well suited to returning substring locations, and if you have time it would be worth reviewing regexp() as a serious possibility.

Related Solutions

MATLAB: Does STRMATCH in MATLAB cause an error for a cell array containing a numeric value

In this example:

str = 9;
strs = strvcat('This is a string array','with two rows');
ind = strmatch(str,strs);

the normal STRMATCH is used, since the first input is not a cell array. In this case, 9 could be used as an ASCII value, and converted to a tab character. That character can then be compared with the other strings.

In this example:

str ={9};
strs = strvcat('This is a cell array of strings','with two rows');
ind = strmatch(str,strs);

@CELL/STRMATCH will be used, since the first input is a cell array. In this case, the code checks that the cell array contains strings, and converts it to a char array:

if iscellstr(str), str = char(str); end

Cell arrays of strings are special cases of cell arrays, which are commonly used to store strings together which have different lengths, and there are many instances where cell arrays of strings and strings can be used interchangeably. However, {9} is not a cell array of strings, so it is not converted to a character array, which leads to the error being thrown by this code:

if ~ischar(str) | ~ischar(strs)
    error('Requires character array or cell array of strings as inputs.')
end

MATLAB: Is it possible to use the UNIQUE function with cell arrays containing empty cells in MATLAB 7.9 (R2009b)

The ability to process empty cells directly with the UNIQUE function is not available in MATLAB 7.9 (R2009b).

As a workaround, you can identify which cells are not empty with the CELLFUN function:

c = {'hello', 'world', [], 'hello', 'MATLAB'}
~cellfun(@isempty, c)

Then use this logical array to index into the original cell array in order to call UNIQUE on only the elements of the cell array which are not empty:

unique(c(~cellfun(@isempty, c)))

Best Answer

Related Solutions

MATLAB: Does STRMATCH in MATLAB cause an error for a cell array containing a numeric value

MATLAB: Is it possible to use the UNIQUE function with cell arrays containing empty cells in MATLAB 7.9 (R2009b)

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