Text file manipulation, find specific lines, find there a string and replace the specific line with new content

Hello Community,

Is there a simple way in matlab to perform the following task?

I have a text file that contains of many datasets that looks like that:

#sp|A00G945|CRER-FG Beta-morph B2 chain PS=Legro soma RB=10653 GN=CWERG PE=20 SV=1

CDMSXXXTGHTJKDLGLSKDJGHLJSDGHFKSJDHFGKSJDFHGKSDJGHKSDJHFGFFF

GHLJSDGHFKSJDHFGKSJDFHGKSDJGHKSDJHFGFFFCDMSXXXTGHTJKDLGLSKDJ

DMSXXXTGHTJKDLGLSKDJDMSXXXTGHTJKDLGLSKDJDMERUTUEZZUUFFF

#sp|P011|CRYAB_Ceta Beta-morph C chain PS=Legro alto RB=5456 GN=CWERF PE=60 SV=2

CDMSXXXTGHTJKDLGLSKDJGHLJSDGHFKSJDHFGKSJDFHGKSDJGHKSDJHFGFFF

GHLJSDGHFKSJDHFGKSJDFHGKSDJGHKSDJHFGFFFCDMSXXXTGHTJKDLGLSKDJ

DMSXXXTGHTJKDLGLSKDJDMSXXXTGHTJKDLGLSKDJDMERUTUEZZUUFFF

...

The beginning of each dataset starts with "#".

I'd like to replace spaces with undescore,

then extract the string between "PS=" and "RB=" (In case of 1. dataset it would give back "Legro_soma"

and replace the line with "#Legro_soma"

fid =fopen('test.txt');

C=textscan(fid,'%s','delimiter','\n');

fclose(fid);

for k=1:numel(C{1,1})

tmp = regexp(C{1,1}(k),'\s'); % find empty spaces

tmp2= strfind(C{1,1}(k),'>');

C{1,1}{k,1}(tmp{1,1}) = '_'; % substitute empty spaces by '_'

end

%Here comes the attemp to extract the string:

idx = strfind(A{u},'PS=');

idend = strfind(A{u},'RB=');

remain = C{1,1}(idx+3:idend-2);

%Replacing the line can be down how?

Thanks for your ideas and help!

Answer 1

[Stephan]

There is a bunch of possibilities to manipulate strings:

https://de.mathworks.com/help/matlab/ref/extractafter.html

https://de.mathworks.com/help/matlab/ref/extractbefore.html

https://de.mathworks.com/help/matlab/ref/extractbetween.html

https://de.mathworks.com/help/matlab/ref/replace.html

https://de.mathworks.com/help/matlab/ref/replacebetween.html

https://de.mathworks.com/help/matlab/ref/strrep.html

https://de.mathworks.com/help/matlab/ref/erase.html

...

One possibility would for example be to replace "PS=" and "RB=" with "" to get rid of them. Another way would work with erase.

[Stephan]

Did you notice that you can accept / vote for useful answers?

Answer 2

[Martin Landesberger]

Hello Stephan,

thanks for your support! It's working now :)