How can I extract multiple values after certain term with regexp?

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Dhani Dharmaprani
评论： Dhani Dharmaprani 2016-3-7
Hi, I am new to using regexp and was wondering how I can extract all 'channel' values in my txt file. A snippet of the file is as follows:
Set 1
Average: 0.976
Channels: 0.973 0.985 0.988 0.989 0.981 0.986 0.99 0.977 0.953 0.992 0.979 0.923
Set 2
Average: 0.983
Channels: 0.978 0.98 0.983 0.985 0.976 0.982 0.985 0.984 0.994 0.991 0.991 0.969
I've found that using the expression '(?<=Channels\D*)\d*\.?\d+\' obtains only the first value after the word channels, so how can I obtain all 12 values for each set of channels?
Thank you kindly in advance!

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采纳的回答

Guillaume
Guillaume 2016-3-7
There are many ways to write a regular expression (see Walter's answer), depending on exactly what restriction you want to place on what is matched and not matched.
A simple way to modify your regular expression is simply to repeat the match pattern until the end of the line:
channelvalues = regexp(filecontent, '(?<=Channels\D*)(\d*\.?\d+(?:\s+|$))+', 'match');
channelvalues = cellfun(@str2num, channelvalues, 'UniformOutput', false)
%if all lines are guaranteed to have the same number of elements:
channelvalues = cell2mat(channelvalues')
  1 个评论
Dhani Dharmaprani
Dhani Dharmaprani 2016-3-7
编辑：Dhani Dharmaprani 2016-3-7
Thank you so much, this works perfectly! And thank you kindly for your explanation, it makes much more sense to me now!

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更多回答（2 个）

Walter Roberson
Walter Roberson 2016-3-7
'(?<=Channels:\s+).+$'
together with the parameter 'dotexceptnewline'
Stephen23
Stephen23 2016-3-7
编辑：Stephen23 2016-3-7
As an alternative to regexp, you can simply read the file data directly using textscan:
fmt = ['Set%f\nAverage:%f\nChannels:',repmat('%f',1,12)];
fid = fopen('test.txt','rt');
M = cell2mat(textscan(fid,fmt));
fclose(fid);
It successfully reads all of the numeric data into one numeric matrix, much quicker than any solution using regexp would. I tested this code using your sample lines, saved into this file:

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