find ( strcmp ( many_different_elements )

Hello, I want to check if any of the elements of a cell CC with 90 elements are in column2 of a matrix w 10k rows. If so, to retrieve the row location.

CC below has four elements

CC={'AB1', 'AB2', 'AB3' ,'AB4'}

I would use

idloc = find(strcmp(databig{:,2}, 'AB1') | strcmp(databig{:,2}, 'AB2')  | strcmp(databig{:,2}, 'AB3')   | strcmp(databig{:,2}, 'AB4') )

But was wondering if there's a nicer way than to write 90 times in the find line

[Mitchell Thurston]

I'm not too experienced with strcmp so there might be a better way, but the easiest way I can think of for this would be

per_index = zeros(numel(CC),1);
for i = 1:length(per_index)
    per_index(i) = any( strcmp(databig{:,2}, CC{i}) );
end
idloc = any(per_index)

I would also recommend using "any" for each strcmp instead of find

[Mitchell Thurston]

I just noticed the end of the first sentence also wanted the row location. The general idea should still work.

Answer 1

[Ryan]

You could create a for loop that checks each element and then do the find outside the four loop for find the rows. Something like this

CC = {'AB1', 'AB2', 'AB3' ,'AB4'};

for ii = 1:length(CC)
    idx(:,ii) = strcmp(databig,CC{ii});
end
[idloc,~] = find(idloc);

Answer 2

[Stephen23]

"But was wondering if there's a nicer way than to write 90 times in the find line"

Of course: forget about repeated STRCMP calls (e.g. in a loop), just use one ISMEMBER call:

https://www.mathworks.com/help/matlab/ref/double.ismember.html

Read its documentation and pay careful attention to the order of its inputs and outputs.

X = ismember(databig(:,2),CC)