这是用正则表达式完成的吗？ 格式化纬度经度

Question

I am trying to format a polygon (several lat/long coordinates connected together) using Leaflet Draw. Here is the format return and what I have done so far:

map.on("draw:drawstop", polyPointToString);              
function polyPointToString(e){
    console.log("Unaltered Coordinates: " + coords);
    polyStringParse = coords.toString().replace(/[^\d,.-]/g, '');             
    console.log("Polyparse: " + polyStringParse);
    polyStringParseRegExp = polyStringParse.replace(/([^,]+[^,]),/g,'$1 ');
    console.log("PolyparseRegExp: " + polyStringParseRegExp);
}

Unaltered Coordinates is this:

//Unaltered Coordinates: LatLng(46.58907, -102.74414),LatLng(46.58907, -102.74414),LatLng(46.58907, -102.74414)

PolyParse is this (only numbers, dashes, and decimal points left):

//Polyparse: 46.58907,-102.74414,46.58907,-102.74414,46.58907,-102.74414

PolyparseRegExpt is this(it keeps removing ALL commas :-( ):

//Polyparse2: 46.58907 -102.74414 46.58907 -102.74414 46.58907 -102.74414

What is need: Comma 1, 3, 5, 7.... etc removed so that I have:

number number, number number, number number,........

Basilcally, every odd numbed comma. right now it's removing all commas for some reason.

Answer 1

The simplest solution (?) - add the other coordinate (preceded by it's comma), making it a pair, capturing it separately without the comma:

([^,]+[^,]),([^,]+[^,],)

replacing it with

$1 $2 (space between and trailing)

reforms the coordinate pair, without the separating comma but leaving the trailing.

See it here at regex101 .

Answer 2

It looks like coords is an array of Leaflet's LatLng s . Using toString() is an odd thing to do, considering that you can use .lat and .lng to access the LatLng 's properties.

It also looks like you're trying to convert your data into WKT (Well-Known-Text) due to yur use of spaces and commas.

So you can convert a LatLng into a WKT coordinate pair with something like:

var latlng = L.latLng(...)
var wktPoint = latlng.lng + ' ' + latlng.lat;

And, if you have an array of LatLng s, you can use Array.prototype.map and Array.prototype.join to great effect here:

var coords = [ L.latLng(...), L.latLng(...), ... ];

var wktLineString = coords.map(function(ll){
    // For every item in the array, return a string.
    // The call to .map() will thus return an array of strings
    return ll.lng + ' ' + ll.lat;

    // Once the array of strings is ready, join those strings
    // with the given separator.
}).join(',');

As I'm assuming you're using WKT, note the swapping of the coordinates so you can have lng-lat instead of lat-lng. Also note you can use toFixed() and the like to have better control of the output.