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Remove unnecessary assignments and array copy #81

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Remove unnecessary assignments and array copy #81

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78d9ca0
Remove unnecessary assignments and array copy
MoonE Apr 4, 2023
8f29a78
Round each coordinate only once
MoonE Apr 5, 2023
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36 changes: 18 additions & 18 deletions src/polyline.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,10 @@ var polyline = {};

function py2_round(value) {
// Google's polyline algorithm uses the same rounding strategy as Python 2, which is different from JS for negative values
return Math.floor(Math.abs(value) + 0.5) * (value >= 0 ? 1 : -1);
return value < 0 ? Math.ceil(value - 0.5) : Math.round(value);
}

function encode(current, previous, factor) {
current = py2_round(current * factor);
previous = py2_round(previous * factor);
function encode(current, previous) {
var coordinate = (current - previous) * 2;
if (coordinate < 0) {
coordinate = -coordinate - 1
Expand Down Expand Up @@ -48,9 +46,9 @@ polyline.decode = function(str, precision) {
lat = 0,
lng = 0,
coordinates = [],
shift = 0,
result = 0,
byte = null,
shift,
result,
byte,
latitude_change,
longitude_change,
factor = Math.pow(10, Number.isInteger(precision) ? precision : 5);
Expand All @@ -60,8 +58,7 @@ polyline.decode = function(str, precision) {
// loop iteration, a single coordinate is decoded.
while (index < str.length) {

// Reset shift, result, and byte
byte = null;
// Reset shift and result
shift = 1;
result = 0;

Expand Down Expand Up @@ -101,15 +98,18 @@ polyline.decode = function(str, precision) {
* @returns {String}
*/
polyline.encode = function(coordinates, precision) {
if (!coordinates.length) { return ''; }

var factor = Math.pow(10, Number.isInteger(precision) ? precision : 5),
output = encode(coordinates[0][0], 0, factor) + encode(coordinates[0][1], 0, factor);

for (var i = 1; i < coordinates.length; i++) {
var a = coordinates[i], b = coordinates[i - 1];
output += encode(a[0], b[0], factor);
output += encode(a[1], b[1], factor);
output = '',
bLat = 0,
bLon = 0;

for (var i = 0; i < coordinates.length; i++) {
var a = coordinates[i];
var aLat = py2_round(a[0] * factor);
var aLon = py2_round(a[1] * factor);
output += encode(aLat, bLat) + encode(aLon, bLon);
bLat = aLat;
bLon = aLon;
}

return output;
Expand All @@ -118,7 +118,7 @@ polyline.encode = function(coordinates, precision) {
function flipped(coords) {
var flipped = [];
for (var i = 0; i < coords.length; i++) {
var coord = coords[i].slice();
var coord = coords[i];
flipped.push([coord[1], coord[0]]);
}
return flipped;
Expand Down