How to separate a portion of filename from a file

How to separate a portion of filename from a file like I have the file 'scrubbed.MOD_D3_AOD_550.20020112.nc' I just want to extract the '20020112' part

Answer 1

[Adam Danz]

[~, fname] = fileparts('scrubbed.MOD_D3_AOD_550.20020112.nc'); 
[~,tok] = regexp(fname,'.(\d+)$','match','tokens'); 
str = tok{1}{1};

[S Roy]

This works perfectly Thank You But I don't quite understand how this works

[Adam Danz]

fileparts() just splits up the path into parts. You can read more here:

https://www.mathworks.com/help/matlab/ref/fileparts.html

regexp() uses regular expressions to find patterns in a string. The "$" symbol indicates that the pattern must be at the end of the string. The pattern should start with a decimal point followed by at least 1 number. The parentheses define a "token" that is returned in 'tok'.

More on regexp: https://www.mathworks.com/help/matlab/ref/regexp.html

[S Roy]

Thanks It really helped.

[Adam Danz]

Glad I could help. The other answers here reminded me to make clear the assumption in my answer that the string of interest is always at the end of the filename (ignoring the final file extension) and is preceeded by a decimal point.

Answer 2

[Stephen23]

Simpler:

>> str = 'scrubbed.MOD_D3_AOD_550.20020112.nc';
>> out = regexp(str,'\d{8}','match','once')
out = 20020112

[S Roy]

Thanks it works fine

[Adam Danz]

It is simpler and assumes that the string of interest will always have 8 digits and that will be the only sub-string with 8 digits.

Answer 3

[Image Analyst]

Try strsplit():

parts = strsplit('scrubbed.MOD_D3_AOD_550.20020112.nc', '.') % Separate in between dots.
yourNumber = parts{end-1} % Take the next to the last one.

[Adam Danz]

This is also simpler than my answer if the assumptions are true that the string of interest is the 2nd to last segment surrounded by decimal points.

[S Roy]

Thanks. Now I know many different ways to do it.

Answer 4

[madhan ravi]

regexp('scrubbed.MOD_D3_AOD_550.20020112.nc',...
    '\d*(?=\.nc)','match','once')