Accessing cell array via factor/index

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Hello,
i have a cell array of 458x3 cells. The first two array columns are numeric, while the last one consists of 4 different strings ('fs','pre','sv','to'). I need to extract the data based on the strings. So, I want to create different groups out of it and make a boxplot for comparison later.
My try was:
data_fs=data{data{:,3} == 'fs',1}
(I access all rows in column 1 and meanwhile I compare the 3rd array column with 'fs')
Well, that obviously doesn't work. Any help is appreciated!
Sorry, for the trivial question. Quite new to MatLab.
thanks!
edit: It is working with boxplot(data,group). But I am still interested in how I can extract the appropriate data sets.

Accepted Answer

Kye Taylor
Kye Taylor on 23 Aug 2012
Edited: Kye Taylor on 23 Aug 2012
You're pretty close in your attempt; it's tricky with the cell indexing and without using strcmp. How about trying this
% array of all strings used as grouping classes
groupLabels = {'fs','pre','sv','to'};
% anonymous function for id'ing rows
f = @(s)data(strcmp(s,data(:,3)),:);
% get the groups
groups = cellfun(f,groupLabels,'UniformOutput',false);

More Answers (2)

Babak
Babak on 23 Aug 2012
Edited: Babak on 23 Aug 2012
You need to use strcmp() to compare strings:
for j=1:size(data,2)
if strcmp(data{j,3},'fs')
% do some stuff here for this case
else if strcmp(data{j,3},'pre')
% do some other stuff here for this case
end
end
end

Matt Fig
Matt Fig on 23 Aug 2012
Edited: Matt Fig on 23 Aug 2012
I assume you mean that the each row in the third column contains one of 'fs','pre','sv',or 'to', not all 4! This snippet finds those rows that have 'fs' in the third column and returns the corresponding first columns of the cell array into a new cell array. If you want all the columns of the matching rows, change the 1 at the end to a colon.
data_fs = data(strcmp(data(:,3),'fs'),1)
  1 Comment
Janett Göhring
Janett Göhring on 23 Aug 2012
thanks! that also helped a lot! strcmp it is ^^

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