MATLAB: Transfer certain rows of a text file into a new text file

text file

I need to transport some lines in my text file, attached as SAMPLEFILE.txt, onto a new text file. The lines I want to transport are the lines that are marked by having a '~' in the 5th column.
For example: 18|PGC000018|0.00360|46.96508|~|14.25|0.869|0.280|0.791|~|0.91|0.107|~|-20.25|77.306|11.596|0.31|0.32|
has a '~' in the 5th column [NAMED AS GalList.morph IN THE CODE BELOW].
My current code is:
load SAMPLEFILE.txt %loads text into workspace
readCatalog( SAMPLEFILE )
fid = fopen( 'SAMPLEFILE.txt');
trashLine = fgets(fid); %Skips the first line
data = textscan(fid, '%f%s%f%f%s%f%f%f%f%f%f%f%f%f%f%f%f%f', 'Delimiter', '|', 'TreatAsEmpty','~');
fclose(fid);
GalList.pgc = data{1};
GalList.name = data{2};
GalList.ra = data{3};
GalList.dec = data{4};
GalList.morph = data{5};
GalList.app_mag = data{6};
GalList.major = data{7};
GalList.abs_mag = data{14};
GalList.dist = data{15};
GalList.err_Dist = data{16};
GalList.err_App_Mag = data{17};
GalList.err_Abs_Mag = data{18};
theta = GalList.ra * pi/12;
phi = GalList.dec * pi/180;
GalaxyList = GalList;
Q1 = GalList.morph;

Best Answer

This will probably do what you want:
content = fileread('samplefile.txt');
linestocopy = regexp(content, '^([^|]*\|){4}~\|.*$', 'match', 'dotexceptnewline', 'lineanchors');
newfile = fopen('copiedlines.txt', 'wt');
fprintf(newfile, strjoin(linestocopy, '\n'));
fclose(newfile);
It uses a regular expression to find all the lines that start by (any number of characters but | followed by | ) repeated four times, followed by ~|, then anything up to the end of the line.
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