Clear Filters
Clear Filters

Parse a cell array of strings without looping

7 views (last 30 days)
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
  6 Comments
per isakson
per isakson on 11 Oct 2012
Edited: per isakson on 11 Oct 2012
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.

Sign in to comment.

Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 11 Oct 2012
Edited: Azzi Abdelmalek on 11 Oct 2012
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))

More Answers (2)

Matt Fig
Matt Fig on 11 Oct 2012
Edited: Matt Fig on 11 Oct 2012
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 on 11 Oct 2012
Edited: per isakson on 11 Oct 2012
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.
  3 Comments
per isakson
per isakson on 11 Oct 2012
Edited: per isakson on 9 Feb 2017
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 on 11 Oct 2012
Perfect. Thanks everyone for your help. I didn't know I could only accept one answer or I would have accepted everyone's.
Justin

Sign in to comment.

Categories

Find more on Data Type Conversion in Help Center and File Exchange

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!