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filter string in the string

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Liger
Liger on 21 Aug 2019
Commented: Liger on 28 Aug 2019
Hello,
I am quietly new with matlab script.
I have a string as example.
str = 'this matlab is a good software, it is a version 9.4 which is equal to 2018a'
objective, I want to filter the number from that string ( so it is "9.4").
Note that I cannot see that number. All i want is to scan that number and show in my workspace.
so the scribt should read the text and identify the number of the version and show in my workspace.
I appreciate your help.
Regards,
LN

  2 Comments

Ted Shultz
Ted Shultz on 21 Aug 2019
Do you not want to also get '2018'? What rule would the code use to exclude this?
Adam
Adam on 21 Aug 2019
doc regexp
should help do this. It takes a bit of getting used to parameterising regular expressions though. There are likely simpler ways depending how robust you want it to be.

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Accepted Answer

Stephan
Stephan on 21 Aug 2019
Edited: Stephan on 21 Aug 2019
str = 'this matlab is a good software, it is a version 9.4 which is equal to 2018a'
str = char(str);
idx = find((uint8(str)>=48 & uint8(str)<=57) | uint8(str)==46 | uint8(str)==32);
res = split(string(str(idx))," ");
res(res=="")=[]
The second line makes sure that it also works with:
str = "this matlab is a good software, it is a version 9.4 which is equal to 2018a"

  3 Comments

Guillaume
Guillaume on 21 Aug 2019
The conversion to uint8 is a waste of time, you could just write
idx = find((str>=48 & str<=57) | str==46 | str==32);
even clearer:
idx = find((str>='0' & str<='9') | str=='.' | str==' ');
you could also use ismember:
idx = find(ismember(str, '0123456789. '));
Stephan
Stephan on 21 Aug 2019
thank you for the hint!
Liger
Liger on 28 Aug 2019
Thank you, i found the anwser so useful

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More Answers (2)

Stephen Cobeldick
Stephen Cobeldick on 21 Aug 2019
Edited: Stephen Cobeldick on 21 Aug 2019
>> str = 'this matlab is a good software, it is a version 9.4 which is equal to 2018a';
>> out = regexp(str,'\d+\.\d+','match','once')
out = 9.4

  1 Comment

Liger
Liger on 28 Aug 2019
Thank you

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Guillaume
Guillaume on 21 Aug 2019
Edited: Guillaume on 21 Aug 2019
Using a regular expression:
numbers = regexp(youstring, '\<\d*\.?\d+\>', 'once')
which will extract any number not attached to text. Allowed formats for number is 123, 123.45, .123

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