Stripping suffix from all elements of string cell array - matlab

Question

I have a cell array containing strings, called old_array. Each element ends with the suffix '.dat'. I want to create a new cell array, called new_array, that has the same elements, but without this suffix.
I know that the following function exists:
[new_array] = arrayfun(func, old_array)
But what do I use for func? I thought about using strsplit(str, '.') and taking the first element of this array, something like:
[new_array] = arrayfun(strsplit(*, '.')[0], old_array)
But what do I place instead of the *? What's the best solution?

Answer 1

If every element in your array ends with .dat, why don't you simply extract all of the characters except the last 4 for each string in your cell array?
new_array = cellfun(#(x) x(1:end-4), old_array, 'UniformOutput', false);
This should return a new cell array stored in new_array where each element loses the last 4 characters of each string from the cell array old_array, which is the string .dat for each string in old_array.
However, if you want to make this more robust and if you want to accommodate any file name, you can use strsplit like what you have in your post. You would have to structure it like so:
%// Use to split up the strings for each cell and store in individual cells
new_array_temp = cellfun(#(x) strsplit(x, '.'), old_array, 'UniformOutput', false);
%// Extract the first cell of each nested cell
new_array = cellfun(#(x) x{1}, new_array_temp, 'UniformOutput', false);
We need to do the first step so that we can return a cell array of cells. Each nested cell within the larger cell array will contain strings that are delimited by . within the nested cell element. You then run the next command so that we extract the first string of each nested cell, which is the file name itself before the ..
Here's an example that shows you how this is run, as well as the intermediate outputs:
old_array = {'Hi.dat', 'how.dat', 'are.dat', 'you.dat'};
new_array_temp = cellfun(#(x) strsplit(x, '.'), old_array, 'UniformOutput', false);
celldisp(new_array_temp);
new_array_temp{1}{1} =
Hi
new_array_temp{1}{2} =
dat
new_array_temp{2}{1} =
how
new_array_temp{2}{2} =
dat
new_array_temp{3}{1} =
are
new_array_temp{3}{2} =
dat
new_array_temp{4}{1} =
you
new_array_temp{4}{2} =
dat
new_array = cellfun(#(x) x{1}, new_array_temp, 'UniformOutput', false);
disp(new_array);
'Hi' 'how' 'are' 'you'
Minor note
Note: strsplit only works for MATLAB R2013a and up. If you want this to work with previous versions of MATLAB, use regexp. Replace the strsplit call within cellfun with this:
new_array_temp = cellfun(#(x) regexp(x, '\.', 'split'), 'UniformOutput', false);
This should basically achieve the same thing as strsplit. However, if you really, really, really, really want to use strsplit, there is an implementation on the MathWorks File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/21710-string-toolkits/content/strings/strsplit.m