CODEWITHSUNDEEP
javascriptnode.js
Jan Gunzenhauser
Jan Gunzenhauser

Reputation: 73

Extract variables from child process output string

I am building an application that uses a child process to make mathematical calculations: 

var child = exec('get_hrv -M -R rr.txt', function(error, stdout) {
    if (error !== null) {
        console.log('exec error: ' + error);
    } else {
        res.send(stdout);       
    }
});

The output (stdout) looks like this: 

NN/RR    = 0.992424
AVNN     = 789.443
SDNN     = 110.386
SDANN    = 0
SDNNIDX  = 110.386
rMSSD    = 73.5775
pNN50    = 36.9231
TOT PWR  = 12272.8
ULF PWR  = 788.161
VLF PWR  = 4603.59
LF PWR   = 4221.97
HF PWR   = 2659.05
LF/HF    = 1.58777

Everything is working as it should, however, this output is a string and I need the values it contains assigned to separate integer variables, e.g. like this: 

var extractedVars = {
    NN/RR: 0.992424
    AVNN: 789.443
    SDNN: 110.386
    SDANN: 0
    SDNNIDX: 110.386
    rMSSD: 73.5775
    pNN50: 36.9231
    TOT PWR: 12272.8
    ULF PWR: 788.161
    VLF PWR: 4603.59
    LF PWR: 4221.97
    HF PWR: 2659.05
    LF/HF: 1.58777
}

How can this be done? Regex?

Upvotes: 0

Views: 144

Answers (2)

Barış Uşaklı
Barış Uşaklı

Reputation: 13532

You can try something like this 

var lines = dataFromProc.split(require('os').EOL);
var data = {};
lines.forEach(function (line) {
    var parts = line.split('=');
    if (parts[1]) {
        data[parts[0].trim()] = parseFloat(parts[1].trim());
    }
});
console.log(data);

Upvotes: 1

Henrik Karlsson
Henrik Karlsson

Reputation: 5733

Since you mentioned regular expressions I wrote a solution using regexp. I'm not sure I would use this solution since the others probably are easier to read, but here it goes anyway. The key goes into capture group 0 and the value into group 1.

var regexp = /([0-9A-Za-z\/ ?]*)= ([0-9\.]*)/;
var extractedVars = {}
data.split(os.EOL).forEach(function (line) {
    var res = regexp.exec(line);
    extractedVars[res[1].trim()] = parseFloat(res[2]);
});

The expression on regexr

Upvotes: 1

Related Questions