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Character restriction in text file

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jgillis16
jgillis16 2015-8-10
编辑： Cedric 2015-8-10
I am trying to restrict a text file by only keeping lines that contain 'M' in the first column.
I wrote the code below, except 'M' cannot be used in str2double. Would there be an alternative way to write this? Code below:
clear all
fidi = fopen('BTM.txt','rt');
Glxc = textscan(fidi, '%s', 'Delimiter','|');
frewind(fidi)
Glxcs = textscan(fidi, '%s', 'EndOfLine','\r\n');
fclose(fidi);
dlen = 2*fix(length(Glxc{:})/2); % Set Row Length
Glxcr = reshape(Glxc{:}(1:dlen), 2, [])'; % Reshape & Transpose
LIdx= (str2double(Glxcr(:,2))<=1813.1) & (str2double(Glxcr(:,1))='M')% Reshape & Transpose
NewGlxc = Glxcs{:}(LIdx,:); % Rows Of New Array
fido = fopen('vcc18M.txt','wt')
fprintf(fido, '%s\n', NewGlxc{:});
fclose(fido)
  2 个评论
Star Strider
Star Strider 2015-8-10
‘... pulling lines that contain 'M' in the first column ...’
Does that mean that you want to keep those lines or discard them?
jgillis16
jgillis16 2015-8-10
keep those lines, discard the rest that don't have 'M' in the first column.

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采纳的回答

Walter Roberson
Walter Roberson 2015-8-10
LIdx = (str2double(Glxcr(:,2))<=1813.1) & ~cellfun(@isempty, regexp(Glxcr(:,1),'^M$'))
If the column only needs to start with 'M' but can contain other characters, use '^M' . If the column only needs to have 'M' somewhere in it, use 'M'

更多回答（1 个）

Cedric
Cedric 2015-8-10
编辑：Cedric 2015-8-10
If you want to keep only the lines which start with the character M, the following would work:
content = fileread( 'BTM.txt' ) ;
content = regexprep( content, '^[^M].*?$\s*', '', 'lineanchors' ) ;
And then you export keeping the original format:
fId = fopen( 'vcc18M.txt', 'w' ) ;
fwrite( fId, content ) ;
fclose( fId ) ;
PS: Will you ultimately want to separate lines like here? Were you able to make this one work by the way?
EDIT : Without knowing more about the content of the file, it is difficult to debug what you wrote, but if Glxcr(:,1) is truly indexing cells which contain elements of the first column of the file, then you probably want to replace
& (str2double(Glxcr(:,1))='M')
with
& strcmp( Glxcr(:,1), 'M' )

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