在Matlab中使用regexp从文本文件返回变量的值 [英] Use regexp in Matlab to return the value of a variable from a text file

问题描述

我正在将一个名为'test.txt'的文本文件读取到Matlab中，其结构如下:

I am reading a text file into Matlab called 'test.txt' which is structured as follows:

$variable1 = answer1; 
$variable2 = answer2;
$variable3 = answer3;

我使用以下代码段将文本文件逐行读入Matlab:

I read the text file into Matlab line by line using the following segment of code:

fid = fopen('test.txt.');
tline = fgetl(fid);
tracks = {};
while ischar(tline)
    tracks{end+1} = regexp(tline, '(?<=^.*\=\s*)(.*)(?=\s*;$)', 'match', 'once');
    tline = fgetl(fid);
end
fclose(fid);

这段代码逐行返回每个变量的值，并输出:

This piece of code returns the value of each variable line by line and would output:

answer1
answer2
answer3

我要做的是修改我的regexp表达式，以便我可以指定要检索的变量的名称，并使Matlab输出分配给指定变量的值.

What I want to do is modify my regexp expression so that I can specify the name of the variable to retrieve and have Matlab output the value assigned to the variable specified.

例如如果我在代码中指定以查找$ variable2的值，Matlab将返回:

E.g. If I specify in my code to find the value of $variable2, Matlab would return:

answer2

致谢

推荐答案

一种可能的解决方案:

function [tracks] = GetAnswer(Filename, VariableName)
fid = fopen(Filename);
tline = fgetl(fid);
tracks = {};

% prefix all $ in VariableName with \ for `regexp` and `regexprep`
VariableName = regexprep(VariableName, '\$', '\\$');

while ischar(tline)
    if (regexp(tline, [ '(', VariableName, ')', '( = )', '(.*)', '(;)' ]))
        tracks{end+1} = regexprep(tline, [ '(', VariableName, ')', '( = )', '(.*)', '(;)' ], '$3');
        % if you want all matches (not only the 1st one),
        % remove the following `break` line.
        break;
    end
    tline = fgetl(fid);
end

fclose(fid);
return

您可以这样称呼:

Answer = GetAnswer('test.txt', '$variable2')

Answer = 
'answer2'

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