CODEWITHSUNDEEP
matlab
user1849133
user1849133

Reputation: 527

Deleted rows with a specified string (MatLab)

To delete rows with a specified string, I read

http://www.mathworks.com/matlabcentral/answers/34567-remove-row-with-matching-string

I did but failed.

text.txt looks like

123     A omit B
2323    C omit D
333         oh

And I coded

fid = fopen('text.txt');
tttt = textscan(fid, '%s %s','delimiter','\t','HeaderLines',0)
tttt(strcmp(tttt{2}, 'omit'), :) = []
strcmp(tttt{2}, 'omit')

But MatLab showed me "Empty cell array: 0-by-3" and 

ans =

     0
     0
     0

I guess the type of file "tttt" is wrong (because I had to write "tttt{2}" rather than tttt(:,2)) but I am not sure.

Upvotes: 1

Views: 1678

Answers (2)

supyo
supyo

Reputation: 3037

If performance is a concern, you might try invoking Unix's sed directly from within Matlab:

system('sed ''/omit/d'' text.txt > output.txt');

Here is the analogous command, calling AWK from within Matlab:

system('awk ''!/omit/'' text.txt > output.txt');

Upvotes: 1

Rody Oldenhuis
Rody Oldenhuis

Reputation: 38032

You are using strcmp(), which compares the equality of two strings. That is not what you are after; you want to check whether some string is a substring of another string. You can use strfind or findstr or regexp or regexprep for that purpose.

ALso, you are not closing your text file. This can lead to all sorts of problems. Make it a habit to always write fid = fopen(...); fclose(fid); as if it is one command, and then continue coding in between.

A small example: 

fid = fopen('text.txt');

    tttt = textscan(fid, '%s %s','delimiter','\t');
    tttt{2}(~cellfun('isempty', strfind(tttt{2}, 'omit'))) = [];

fclose(fid);

EDIT: based on your comments, I think you want to do this: 

fid = fopen('text.txt');

% Modified importcommand
tttt = textscan(fid, '%s%s',...
    'delimiter','\t',....
    'CollectOutput', true);
tttt = tttt{1};

% Find rows for deletion 
inds = ~cellfun('isempty', strfind(tttt(:,2), 'omit'));

% aaaand...kill them!    
tttt(inds,:) = [];


fclose(fid);

Upvotes: 3

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