Javascript - String to Coordinates Array

Question

I'm new to Javascript and i'm having some issues converting a string to an array of coordinates values .

This is my string (Temporary - the string might have more/less coordinates) :

var str = "12:13.94:13:14.9:";

each coordinate are separated by a ":" , where

str[0] = x1;
str[1] = y1;
str[2] = x2;
str[3] = y2;
.................

I want it to return a 2D array of coordinates as :

var cArray = [[12,13.94],[13,14.9].........];

Is there any way to do this ?

I tried :

var cString = coorStr.split(":");

But it just returns an array of string,

This is what i have so far : https://jsfiddle.net/mLskwxyj/

`var cArray = [cString.slice(0, 2), cString.slice(2, 4)]`? There is no single function to do what you want. — Bergi, Feb 25 '16 at 21:32
`JSON.parse("["+"12:13.94:13:14.9:".replace(/([\d\.]+):([\d\.]+)/g,"[$1,$2]").replace(":",",").slice(0,-1)+"]")` — dandavis, Feb 25 '16 at 21:51
http://stackoverflow.com/questions/4492385/how-to-convert-simple-array-into-two-dimensional-arraymatrix-in-javascript-or — epascarello, Feb 25 '16 at 21:51

score 3 · Answer 1 · edited May 23 '17 at 12:07

tadman's answer gives a way to parse your string into an array of numbers:

var str = '12:13,94:13:14,9';
var num = str.split(':').map(Number);

For a generic way to split this array into [x, y] pairs, this answer provides a terse solution. I've slightly modified it below (to remove the Lodash dependency):

var coords = num.reduce(function (r, v, i, a) {
  // on every even element, grab a pair of numbers and 
  // add to the result
  if (i % 2 === 0)
    r.push(a.slice(i, i + 2));

  return r;
}, []);

Here is a working example. Note that a for loop with a pre-allocated result array will be more performant. I just wanted to provide a way to do it in a single statement.

tadman · Answer 2 · 2016-02-25T21:34:55.710

1

This is a bit clunky but arranges them as you want:

var str = "12:13,94:13:14,9:";

var split = str.replace(/,/g, '.').split(':').map(Number);

var result = [
  [ split[0], split[1] ],
  [ split[2], split[3] ],
];

console.log(result);
// [ [ 12, 13.94 ], [ 13, 14.9 ] ]

Accounts for the European style use of , in numbers.

Update: Added .map(Number) as suggested.

edited Feb 25 '16 at 21:34

answered Feb 25 '16 at 21:33

tadman

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you might want to add a `.map(Number)` – Bergi Feb 25 '16 at 21:33
Yeah, did it a more hack way, but fixed now. Great call. Thanks! – tadman Feb 25 '16 at 21:36
@tadman - will this work in a for loop in the event where the string has more coordinates – Jimmy Feb 25 '16 at 21:38
1

@Jimmy: Of course not. If you need a loop, use a loop instead of the array literal. See [this question](http://stackoverflow.com/q/8495687/1048572) (and those linked from there) for generic solutions of all kinds. – Bergi Feb 25 '16 at 21:39
Is there an example for the for loop code . I'm trying in js.do but getting error in my forloop for(int i = 0 ; i – Jimmy Feb 25 '16 at 21:41
"Getting an error" is the least helpful thing you can say. Try and be specific about the nature of the error, such as the actual text you're getting. – tadman Feb 25 '16 at 21:49
Have a look at [this example](http://stackoverflow.com/questions/8566667/split-javascript-array-in-chunks-using-underscore-js) for inspiration. – tadman Feb 25 '16 at 21:50

Javascript - String to Coordinates Array

2 Answers2