Javascript: split string into 2d array

Question

I have a string of month and years:

var months= "2010_1,2010_3,2011_4,2011_7";

I want to make this into a 2d array with the year in the first position of each array and the month in the second position. In other words, I want to end up with this:

var monthArray2d = [[2010,1],[2010,3][2011,4],[2011,7]];

The way I do this currently is:

//array of selected months
var monthArray = months.split(",");

//split each selected month into [year, month] array
var monthArray2d = new Array();
for (var i = 0; i < monthArray.length; i++) {
    monthArray2d[i] = monthArray[i].split("_");

Is there a way to condense that code so that I never need to use the monthArray var?

georg · Accepted Answer · 2019-01-23 01:08:30Z

12

You can use replace to get more compact code:

var months= "2010_1,2010_3,2011_4,2011_7";
var monthArray2d = []

months.replace(/(\d+)_(\d+)/g, function($0, $1, $2) {
    monthArray2d.push([parseInt($1), parseInt($2)]);
})

or map if your target browser supports it:

monthArray2d = months.split(",").map(function(e) {
    return e.split("_").map(Number);
})

Basically, the first function looks for year/month patterns "digits underscore digits", and stores each found substring in an array. Of course, you can use other delimiters instead of underscore. The function doesn't care about the values' delimiter (comma), so that it can be whatever. Example:

var months= "2010/1 ... 2010/3 ... 2011/4";
months.replace(/(\d+)\/(\d+)/g, function($0, $1, $2) {
    monthArray2d.push([parseInt($1), parseInt($2)]);
})

edited Jan 23, 2019 at 1:08

answered Dec 21, 2011 at 17:59

georg

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2 Comments

JBJ Over a year ago

Hi, could you elaborate a bit more on the first function? How would one get this to work if the separators were not "_" and ",", but some other character for example "x" and "y"?

georg Over a year ago

@JBJ: I've added some explanations to the post... let me know if you have questions.

Shawn Chin · Accepted Answer · 2011-12-22 10:19:38Z

10

If condensed is what you're after:

var month_array = months.split(",").map(function(x){return x.split("_")});

edited Dec 22, 2011 at 10:19

answered Dec 21, 2011 at 18:00

Shawn Chin

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Comments

John Topley · Accepted Answer · 2012-01-18 13:16:25Z

6

JavaScript is another dynamic language and its variable type allows you to keep anything wherever you like. You did the split right, now just split that string with _ and put it back in there.

See this example:

var months= "2010_1,2010_3,2011_4,2011_7";

var monthArray = months.split(",");

for (var i = 0; i < monthArray.length; i++) {
   monthArray[i] = monthArray[i].split("_");
}

console.log(monthArray);

I don't know what you mean by not to use monthArray. The code above is the least you can do, probably!

edited Jan 18, 2012 at 13:16

John Topley

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answered Dec 21, 2011 at 17:52

Abdul Munim

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Comments

kennebec · Accepted Answer · 2011-12-21 18:21:41Z

1

Splitting each split is a sensible thing to do- you can use a regular expression to match the underscore separated numbers, and insert each pair in its own array pushed to the month array-

but I don't see an improvement over your code:

var s= "2010_1,2010_3,2011_4,2011_7",

A= [], rx=/(\d+)_(\d+)/g;

while((M= rx.exec(s))!= null){
    A.push([M[1], M[2]]);
}


/*  returned value: (Array)
[[2010,1],[2010,3],[2011,4],[2011,7]]
*/

answered Dec 21, 2011 at 18:21

kennebec

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