在MATLAB中快速分割字符串

Question

I've been using MATLAB to read through a bunch of output files and have noticed that it was reading the files fairly slowly in comparison to a reader that I wrote in Python for the same files (on the order of 120s for MATLAB, 4s for Python on the same set). The files have a combination of letters and numbers, where the numbers I actually want each have a unique string on the same line, but there is no real pattern to the rest of the file. Is there a faster way to read in non-uniformly formatted text files in MATLAB?

I tried using the code profiler in MATLAB to see what takes the most time, and it seemed to be the strfind and strsplit functions. Deeper down, the strfun\\private\\strescape seems to be the culprit which takes up around 50% of the time, which is called by strsplit function.

I am currently using a combination of strfind and strsplit in order to search through a file for 5 specific strings, then convert the string after it into a double.

lots of text before this

   ####  unique identifying text here

lots of text before this

sometext  X = #####
          Y = #####
          Z = #####
more text = ######

I am iterating through the file with approximately the following code, repeated for each number that is being found.

fid=fopen(filename)
tline=fgets(fid)
while ischar(tline)
    if ~isempty(strfind(tline('X =')))
        tempstring=strsplit(tline(13:length(tline)),' ');
        result=str2double(char(tempstring(2)));
    end
    tline=fgets(fid);
end

Answer 1

I'm guessing this will be a bit faster, but maybe not by much.

s = fileread('texto');
[X,s] = strtok(strsplit(s, "X = "){2}); X = str2num(X);
[Y,s] = strtok(strsplit(s, "Y = "){2}); Y = str2num(Y);
[Z,s] = strtok(strsplit(s, "Z = "){2}); Z = str2num(Z);

Obviously this is highly specific to your text example. You haven't given me any more info on how the variables might change etc so presumably you'll have to implement try/catch blocks if files are not consistent etc.

PS. This is octave syntax which allows chaining operations. For matlab, split them into separate operations as appropriate.

EDIT: ach, nevermind, here's the matlab compatible one too. :)

s = fileread('texto');
C = strsplit(s, 'X = '); [X,s] = strtok(C{2}); X = str2num(X);
C = strsplit(s, 'Y = '); [Y,s] = strtok(C{2}); Y = str2num(Y);
C = strsplit(s, 'Z = '); [Z,s] = strtok(C{2}); Z = str2num(Z);