MATLAB Answers

Lucas
0

Get number from a string

Asked by Lucas
on 12 Sep 2012
I have a string that looks like this
I_am_a_String.562
I need to be able to pull the number out of that, and I was using the following to do so:
num = regexp(str, '\d+', 'match');
and that worked will I ran into strings like:
When lpdlogic21 is true....
and I started getting numbers that I didn't want, so I switched it to this:
num = regexp(lines{1}{jj}, '(?<words>\w*).(?<ID>\d*)', 'names');
but this didn't work for the off string either. It gave me num with about 20 entries in it. So my question is what can I use so I only get answers for the first string but none of the others. This is a basic question and I know I should know this by now, but I'm drawing a blank right now.

  1 Comment

Matt Fig
on 12 Sep 2012
What others? You need to give a rule for deciding when to return a number and when not to return a number.

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1 Answer

Matt Fig
Answer by Matt Fig
on 12 Sep 2012
Edited by Matt Fig
on 12 Sep 2012
 Accepted Answer

What do you mean it didn't work. Seems to work here. So what numbers do you want? Only numbers that are after a '.' or what (use: '\.\d+')? Be specific!
str = 'When lpdlogic21 is true....';
num = regexp(str, '\d+', 'match')
num =
'21'

  1 Comment

Matt Fig
on 12 Sep 2012
O.k., so the rule is: if the string has any spaces whatsoever, return nothing. If it has no spaces return all numbers following a decimal. Got it.
num = {};
if ~any(isspace(str))
num = regexp(T, '(?<=\.)\d+', 'match');
end

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