how to use regexp to get the last characters of a line

file = uigetfile('*.txt','Select the text file to parse');
fid=fopen(file)

text=fileread(file)
expr='[^\n]*Machine Name=[^\n]*';
matches=regexp(text, expr,'match');
disp(matches)

I have a really long complicated text file that I want to parse. It is really long and is a list of lines. There are no comma delimiters, but the machine name that I am looking for is always at the end of the line ... like

121212323 : Machine Name = roboDog
121222323 : Machine IOS = Android

The code above was my attempt to desplay the lines which contained the keyword. It wouldn't work, but I would ideally like each Machine Name to be stored in a vector like machineName={'roboDog' ; 'roboCat'}

Thanks!

Answer 1

[the cyclist]

Your definition of expr does not have a space between "Machine Name" and the equals sign, but your text example does. When I put that space in, it found the match.

[Lucy Cathwell]

Thank you, I have it correct in my actual code, for some reason my code returns the second half of the text file..... but I really want the code to take the end of the line such as roboDog..

[the cyclist]

There's probably a more efficient way, but this slight change to your code will grab just the machine name:

expr='Name =[^\n]*';
matches=regexp(text, expr,'match')
matches = matches{:}(8:end);

[Lucy Cathwell]

Expected one output from a curly brace or dot indexing expression, but there were 60 results

and could you please maybe send a link where I could read about the annotation?

[the cyclist]

I think the following "lookback" expression is probably the most efficient way:

expr='(?<=Name = )\w*';
matches=regexp(text, expr,'match')

[the cyclist]

Sorry, the error you got above was due to the fact that I was testing on just one line of code, instead of your multiple-line file.

Regardless, my follow-up solution is superior, and won't spin off that error.

[Lucy Cathwell]

matches =

  0×0 empty cell array

Did this happen for you too? there are definitely plenty of matches

[the cyclist]

With the attached text file, and this code:

fid=fopen('machine.txt');
text=fileread('machine.txt')

expr='(?<=Name = )\w*';
matches=regexp(text, expr,'match')

I get a 1x2 cell array:

matches =

  1×2 cell array

    {'roboDog'}    {'roboCat'}

[Walter Roberson]

I suspect that machine names might not strictly match \w as that does not include '-' for example. I suggest

expr = '(?<=Name =\s*).*?(?=\s*)$';
matches = regexp(text, expr, 'match', 'lineanchors', 'dotexceptnewline')

This strips out leading and trailing whitespace and accepts anything between