Write a function to extracts number between 2 letters?

2016 9 7
3 个回答
回答已采纳
更新时间：2016 9 8
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I am trying to write a MATLAB code that extracts a 3 digit number in between two letters. the tricky part is that the letter after the number could be either (s)or(h)
E.g 1 the filename is 'rfc_f123sars.tif' this should extract 123 which is between _f and s E.g 2 the filename is 'rfc_f456hars.tif' this should extract 456 which is between _f and h Thanks :)

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per isakson
per isakson 2016-9-7
编辑：per isakson 2016-9-7

0 个投票

Without comments
>> str = 'rfc_f123sars.tif' ;
>> regexp( str, '(?<=_f)\d{3}(?=[sh]{1})', 'match', 'once' )
ans =
123
and slightly different; replace [sh]{1} by (s|h), which is a tiny bit cleaner
>> str = 'rfc_f456hars.tif';
>> regexp( str, '(?<=_f)\d{3}(?=(s|h))', 'match', 'once' )
ans =
456
If regexp returns empty set out=0

更多回答（2 个）

Walter Roberson
Walter Roberson 2016-9-7

0 个投票

regexp(filename, '\d\d\d', 'match')
or if you want to be more secure,
regexp(filename, '(?<=[A-Za-z])\d\d\d(?=[A-Za-z])', 'match')
Guillaume
Guillaume 2016-9-7
编辑：Guillaume 2016-9-7

0 个投票

This is trivial with a regular expression:
nstr = regexp(filename, '(?<=_f)\d+(?=(s|h))', 'match', 'once');
if isempty(nstr)
n = 0;
else
n = str2double(nstr);
end
The regular expression matches a sequence of one or more digit, preceded by _f, followed by h or s.

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