MATLAB: Delete the string symbols on specific line with special symbol.

delete symbol on text fileMATLAB

Hi I have file fomated like that.
# 1996  3  4  9 58 11.0 20.2810 106.3000  20.8  2.7 0.0 0.0 0.5    1
PLV   12.20 1.00 Pg
PLV   21.00 0.75 Sg
HNV   16.20 1.00 Pg
HNV   28.40 0.75 Sg
# 1996  3 29 10 34 43.4 20.8820 107.2830  28.5  2.6 0.0 0.0 0.7    2
PLV   12.20 1.00 Pg
PLV   20.60 0.75 Sg
Now I need to remove the number on line have symbol "#" from
# 1996  3  4  9 58 11.0 20.2810 106.3000  20.8  2.7 0.0 0.0 0.5    1
to 
#    1
Mean that all so thing after "#" to last number need to be remove (between # and number have 4 <space>). Final I need the file like that
#    1
PLV   12.20 1.00 Pg
PLV   21.00 0.75 Sg
HNV   16.20 1.00 Pg
HNV   28.40 0.75 Sg
#    2
PLV   12.20 1.00 Pg
PLV   20.60 0.75 Sg
Any one can help me! I try few way but it remove all or change the string only.

Best Answer

Here we use fileread() to read your txt file into matlab and then we put each line of text into a cell array. Using regexp() we find which lines start with the pattern "# ****" where the asterisks are numbers. Then we replace those lines with your new pattern: "# *" and write it to a new text file using fprintf(). 
txtFile = 'C:\Users\name\Documents\MATLAB\mlc.txt'; 
% Read file and store each line in a cell
txt = fileread(txtFile);
txtCell = strsplit(txt, newline)'; 
% Find rows that start with '# ####'
hasPattern = regexp(txtCell, '# \d+');          %this searches for "#' followed by 1 space and at least 1 number.
rowIdx = find(~cellfun(@isempty, hasPattern));  %row numbers that will be replaced
% Replace the rows with new text
newText = strsplit(sprintf('#    %d|', 1:length(rowIdx)), '|');   %Here's where you create the new text; ignore last element. 
txtCell(rowIdx)  = newText(1:end-1); 
txtCell = cellfun(@(x)sprintf('%s\n',x), txtCell, 'UniformOutput', false); %add 'newrow' char
% Write text to new file (or you could overwrite the old one).
newFile = 'C:\Users\name\Documents\MATLAB\mlcNEW.txt'; 
fid = fopen(newFile, 'wt'); 
fprintf(fid, [txtCell{:}]);
fclose(fid);
Your new txt file will look like this
#    1
PLV   12.20 1.00 Pg
PLV   21.00 0.75 Sg
HNV   16.20 1.00 Pg
HNV   28.40 0.75 Sg
#    2
PLV   12.20 1.00 Pg
PLV   20.60 0.75 Sg
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