Extracting number from a string
929 views (last 30 days)
Show older comments
How can I extract the number 1 from the string 'M1' ?
0 Comments
Accepted Answer
Stephen23
on 16 Dec 2016
Here are two very simple methods:
>> str = 'M1';
>> sscanf(str,'M%d')
ans = 1
>> str(2)-'0'
ans = 1
2 Comments
More Answers (3)
Image Analyst
on 16 Dec 2016
Here are two ways, depending on if you want the extracted "1" to be a character (string) or a number:
str = 'M1' % First define the string.
str1 = str(2) % Gives a character
dbl1 = str2double(str(2)) % Give a number (double)
Pierre Harouimi
on 2 Nov 2022
2 Comments
Image Analyst
on 2 Nov 2022
Edited: Image Analyst
on 2 Nov 2022
Example:
string = 'abc123def456789ghi'
numbers = str2double(extract(string, digitsPattern))
It would be nice if they made a little wrapper function for that, since it's hard to remember. Something simple like
numbers = extractNumbers(string);
would be easier for most people I think, than having to know about digitsPattern, extract, str2double, and then having to nest them all together.
Stephen23
on 3 Nov 2022
Edited: Stephen23
on 3 Nov 2022
"Something simple like... would be easier for most people I think..."
The devil is in the details, because it really depends on what you define as a "number". Some users will want to match fractional digits (which probably means selecting for e.g. comma vs dot vs comma|dot), whereas others will want to match only integers and to treat commas/dots as non-numeric. Ditto exponent notation, NaNs, Infs, other bases, fixed-width numbers, various Unicode minus/plus signs, etc.
So it turns out to be not very simple at all, once the different "number" formats are considered. The user specifying a regular expression or MATLAB pattern is one way to give them that control, by making those choices explicit.
See Also
Categories
Find more on Characters and Strings in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!