How to select a part of a string OR another with REGEXP in MATLAB

Question

I've been trying to solve this problem in the last few days with no success. I have the following string:

   comment = '#disabled, Fc = 200Hz'

What I need to do is: if there's the string 'disabled' it needs to be matched. Otherwise I need to match the number that comes before 'Hz'.

The closest solution I found so far was:

  regexpi(comment,'\<#disabled\>|\w*Hz\>','match') ;

It will match the word '#disabled' or anything that comes before 'Hz'. Problem is that when it first finds '#disabled#' it copies also the result '200Hz'.

So I'm getting:

ans = '#disabled' '200Hz'

Summing up, I need to select only the 'disabled' part of a string if there is one, otherwise I need to get the number before 'Hz'.

Can someone give me a hand ?

you are limited to one line...?

Adiel
– Adiel

2014-09-29 09:06:35 +00:00
Commented Sep 29, 2014 at 9:06 — Adiel
– Adiel, Commented Sep 29, 2014 at 9:06
No, actually I'm not.

pfpietro
– pfpietro

2014-09-29 09:11:04 +00:00
Commented Sep 29, 2014 at 9:11 — pfpietro
– pfpietro, Commented Sep 29, 2014 at 9:11

Oleg · Accepted Answer · 2014-09-29 09:34:58Z

5

Suppose your input is:

comment = {'#disabled, Fc = 200Hz';
                      'Fc = 300Hz'}

The regular expression (match disabled if follows # otherwise match digits if they are followed by Hz):

regexp(comment, '(?<=^#)disabled|\d+(?=Hz)','match','once')

Explaining it:

^# - match # at the beginning of the line
(?<=expr)disabled - match disabled if follows expr
expr1 | expr2 - otherwise match expr2
\d+ - match 1 or more digits, equivalently [0-9]+
expr(?=Hz) - match expr only if followed by 'Hz'

Diagram:

Regular expression visualization

Debuggex Demo

edited Sep 29, 2014 at 9:34

answered Sep 29, 2014 at 9:14

Oleg

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1 Comment

pfpietro Over a year ago

Could you explain the matching expression ?

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