Parse a cell array of strings without looping

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Justin Solomon
Justin Solomon 2012-10-11
编辑： per isakson 2017-2-9
I've got a nx1 cell array of strings that correspond to spatial coordinates. Here's an example where n=4,
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
Each row of the cell array is a string containing x,y, and z coordinates separated by a comma. I need to parse each string to separate the coordinates, convert the coordinates to numbers, do an operation on them, then put them back in their original format. Is there a way to do this without looping through each row of the cell array? Any tips or insight would be greatly appreciated.
Regards, Justin
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per isakson
per isakson 2012-10-11
编辑：per isakson 2012-10-11
With 'Headerlines' and 'N' of textscan it would still be possible to read and parse in one step. However, you need to find out the values of the two first.

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采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2012-10-11
编辑：Azzi Abdelmalek 2012-10-11
clear
A={'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'}
B=cellfun(@(x) regexp(x,',','split'),A,'uni',false)
out=cell2mat(cellfun(@(x) [cellfun(@(y) str2num(y),x)],B,'uni',false))
%or easier
out=str2num(cell2mat(A))

更多回答（2 个）

Matt Fig
Matt Fig 2012-10-11
编辑：Matt Fig 2012-10-11
C = {'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'};
% Extract the numbers:
D = cellfun(@str2num,C,'Un',0);
% Do the 'operation' on the coords with cellfun:
E = cellfun(@(x) x+[1 2 3],D,'Un',0)
% Put them back in original format.
F = cellfun(@(x) sprintf('%.4f,',x),E,'Un',0)
Note that the step from D to E is ambiguous given your description, but you get the idea.
per isakson
per isakson 2012-10-11
编辑：per isakson 2012-10-11
On possibility for your first step - if the file is not huge:
str = {
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
'122.8233,216.1323,671.8740'
};
M = str2num( char(str) );
or I didn't get it.
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per isakson
per isakson 2012-10-11
编辑：per isakson 2017-2-9
cellstr( num2str( M, '%f,%f,%f\n' ) )
However, write the numerical array directly to the file with fprintf in a loop I guess that fast enough. Otherwise, transpose the numerical array and write with fprintf, but only if profile showed that it could be worth the trouble.
Justin Solomon
Justin Solomon 2012-10-11
Perfect. Thanks everyone for your help. I didn't know I could only accept one answer or I would have accepted everyone's.
Justin

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