MATLAB: A simple regex error

MATLABregexp

Hi:

I have a simple expression and trying to do a regexp, but it fails. I do not understand why the first regexp fails while the second one succeeds.:

>> str1='peak memory used        124.63 megabytes';
>> tokens=regexp(str1,'peak\s*memory\s*use(\s)*\d')  
tokens =
       []
>> tokens=regexp(str1,'peak\s*memory\s*use(\s)*')  
tokens =
       1

Best Answer

use

tokens=regexp(str1,'peak\s*memory\s*use(\s)*d')

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MATLAB: Extracting consecutive digits using regexp

These two returns "123"

%%

cac = regexp('ITEM 123', '.+?(\d+)', 'tokens' )
%%
cac = regexp('ITEM 123', '[^\d]+(\d+)', 'tokens' )

First, '.+' matches anything up til the end of the text, next it gives back just as little as needed to match '(\d+)' , which is one digit.

'.+?' matches as little as needed so that '(\d+)' is able to match the following text.

I prefer '[^\d]+(\d+)'

Or why not just

cac = regexp('ITEM 123', '\d+', 'match' )

MATLAB: Scan a pattern of characters from a string

ord1 = regexp(tline, 'SSD\d+', 'match'); %if you want SSD returned as part of the match
ord1 = regexp(tline, (?<=SSD)\d+', 'match'); %if you just want the number
ord1 = regexp(tline, SSD(\d+), 'tokens', 'once'); just the number, using capture

It is '\d+' to match numbers, the slash is important. '(?<=)' tells the regex engine to look for the pattern preceding a match, but in your regexp you had nothing for the match.

Best Answer

Related Solutions

MATLAB: Extracting consecutive digits using regexp

MATLAB: Scan a pattern of characters from a string

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