# Extract numbers from char type

11 views (last 30 days)
Yoseph on 18 Oct 2022
Commented: Star Strider on 19 Oct 2022
how can I extract the numbers from a character array value of '4.64 km' and return them as 4.64?

Star Strider on 18 Oct 2022
Edited: Star Strider on 18 Oct 2022
Probably the easiest way —
s = '4.64 km';
c = regexp(s, '\d*\.\d*|\d*', 'match')
c = 1×1 cell array
{'4.64'}
n = str2double(c)
n = 4.6400
EDIT — (18 Oct 2022 at 19:38)
In the event any of the numbers are negative —
s = '4.64 -42 2 -3.14 km';
c = regexp(s, '(\-\d*|\d*)\.\d*|(\-\d*|\d*)', 'match')
c = 1×4 cell array
{'4.64'} {'-42'} {'2'} {'-3.14'}
n = str2double(c)
n = 1×4
4.6400 -42.0000 2.0000 -3.1400
.
Star Strider on 19 Oct 2022
I saw that and wondered, however I did not change my answer, and just learned from the important parts of your syntax.

David Hill on 18 Oct 2022
a='4.65 km';
r=regexp(a,'\d*[.]*\d*','match');
str2num(r{1})
ans = 4.6500

Les Beckham on 18 Oct 2022
Or, in one line of code:
s = '4.64 km';
num = sscanf(s, '%f') % num will be a double
num = 4.6400
Walter Roberson on 18 Oct 2022
Yes this works well when the number is at the beginning. You can also put literal text into the format if you expect an exact match.
The suggestions to use regexp to extract the text of the number work well when you need flexibility.
In cases where you have tables of text see textscan() which can be used on a character vector that has embedded newlines.

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