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Extreact Information from a String

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Christian Berwanger
评论： Jos (10584) 2019-8-5
Hello, I do have the following Code
d = dir('/home/user/Documents/Data*.inp');
names = {d.name}
which gives me an Array of Strings.
names(1) is like = "Data_c11_t3.322111_id01111_Units.inp"
names(2) is like = "Data_c101_t4.32111_id01112_Units.inp"
etc.
Now I want to extract the time, which is in the name after "t". How can I extract the time in such a format?
Any suggestions?

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采纳的回答

KL
KL 2017-11-2
编辑：KL 2017-11-2
regexp would be the best idea, I've no big experiences with it, I'll give it a shot anyway,
names = {'Data_c11_t3.322111_id01111_Units.inp';'Data_c101_t4.32111_id01112_Units.inp'};
t = regexp(names,'[0-9]+\.+[0-9*]+','match')
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Guillaume
Guillaume 2017-11-3
To each their own opinion of course. Regular expressions are designed to extract specific patterns in strings, which, in my opinion is exactly the problem at hand.
Christian Berwanger
Christian Berwanger 2017-11-8
Ok. This worked for me. Thank you. I do have still a question:
Can you please explain me how this worked? I searched up regexp on Mathworks documentation. But honestly I still don't really understand why this one works.
To Guilaume: It extraced only the time. Even I have more numbers in the name. Thats why I am asking how this works as I don't see any reason to just take the numbers from time.

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更多回答（2 个）

Jos (10584)
Jos (10584) 2017-11-3
Use a sscanf to read the number between the _t and _id, ignoring the varying number after the _c. Use cellfun to apply this to all cells:
names = {'Data_c11_t3.322111_id01111_Units.inp' ; 'Data_c101_t4.32111_id01112_Units.inp'} ;
T = cellfun(@(N) sscanf(N,'Data_c%*d_t%f_id'), names) % "%*d" = the * means skip
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Coco Newton
Coco Newton 2019-8-2
@Jos, this is a great answer
How would I adapt the sscanf formatSpec to extract 130 as a numeric value from this string? I have attached the string array variable that this is example string is taken from.
'Position: (19.59862|1.8|53.84677)Rotation: (0 | 130 | 0)'
Many thanks!
Jos (10584)
Jos (10584) 2019-8-5
Thanks :-) Something along these lines should work for your input
str = 'Position: (19.59862|1.8|53.84677)Rotation: (0 | 130 | 0)'
A = sscanf(str, 'Position: (%*f|%*f|%*f)Rotation: (%*d | %d | %*d)')

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KSSV
KSSV 2017-11-2
编辑：KSSV 2017-11-2
str = 'Data_c11_t3.322111_id01111_Units.inp' ;
idx = strfind(str,'_') ;
str2num(str(idx(2)+2:idx(3)-1))
Using regexp:
str = 'Data_c11_t3.322111_id01111_Units.inp' ;
N = str2num( regexprep( str, {'\D*([\d\.]+\d)[^\d]*', '[^\d\.]*'}, {'$1 ', ' '} ) ) ;
t = N(2)
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KSSV
KSSV 2017-11-2
What is filename? Can you copy it?
Christian Berwanger
Christian Berwanger 2017-11-3
I do have it in a for loop. its like
for i = 1:length(names)
fileName = names(i);
idx = strfind(fileName,'_') ;
time = str2DOUBLLE(fileName(idx(2)+2:idx(3)-1));
end
so filename is in the first iteration "Data_c11_t3.322111_id01111_Units.inp"
in the second iteration: "Data_c101_t4.32111_id01112_Units.inp"
and so on.

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