turf - npm Package Versions

3.0.1

This is a big change in Turf! 3.0.0 is a release that targets the development cycle of Turf, letting us work on it more and release more often.

Monorepo

Turf 3.x and forward is a monorepo project. We publish lots of little modules as usual, but there's one repo - turfjs/turf - that contains all the code and the issues for the Turf source code. We use lerna to link these packages together and make sure they work.

Why? We already had internal turf modules, like turf-meta, and development was harder and harder - we had a bunch of custom scripts to do releases and tests, and these were just written for Turf. Lerna is from the very popular and very well-maintained babel project, and it works really well, and reduces maintainer sadness.

Simplicity

Turf grew a bunch of modules that weren't totally necessary, or were expressing only a line or two of JavaScript. We want to make things easier, but these modules didn't make code more expressive and they hid complexity where it didn't need to be hidden. Turf 3.x focuses on the core functionalities we need, making sure they're tested and performant.

turf-erase has been renamed turf-difference to make its name more similar to the equivalents in other libraries.

Removed modules: merge, sum, min, max, average, median, variance, deviation, filter, remove, jenks, quantile. See the upgrade guide below for replacements.

Upgrading from v2

If you were using turf-merge

turf-merge repeatedly called turf-union on an array of polygons. Here's how to implement the same thing without the special module

var clone = require('clone');
var union = require('turf-union');
function merge(polygons) {
  var merged = clone(polygons.features[0]), features = polygons.features;
  for (var i = 0, len = features.length; i < len; i++) {
    var poly = features[i];
    if (poly.geometry) merged = union(merged, poly);
  }
  return merged;
}

An alternative method that merges pairs of features recursively. With large numbers and similar complexity of input geometries this can speed up run time by factor 10. Choose depending on your use case.

var union = require('turf-union');
function mergeBin(polygons) {
  var features = polygons.features;

  do {
    var merged = [], len = features.length;
    for (var i = 0; i < len-1; i += 2) {
      merged.push(turf.union(features[i], features[i+1]));
    }
    if (len % 2 !== 0) {
      merged.push(features[len-1]);
    }
    features = merged;
  } while(features.length > 1);

  return features[0];
}

If you were using turf-sum, min, max, average, median, variance, deviation

The turf-collect method provides the core of these statistical methods and lets you bring your own statistical library, like simple-statistics, science.js, or others.

For example, here's how to find the median of matched values with simple-statistics. Finding other statistics, like variance, mean, and so on simply use other methods from the statistics library.

var ss = require('simple-statistics');
var turf = require('@turf/turf');

var poly1 = turf.polygon([[[0,0],[10,0],[10,10],[0,10],[0,0]]]);
var poly2 = turf.polygon([[[10,0],[20,10],[20,20],[20,0],[10,0]]]);
var polyFC = turf.featureCollection([poly1, poly2]);
var pt1 = turf.point([5,5], {population: 200});
var pt2 = turf.point([1,3], {population: 600});
var pt3 = turf.point([14,2], {population: 100});
var pt4 = turf.point([13,1], {population: 200});
var pt5 = turf.point([19,7], {population: 300});
var ptFC = turf.featureCollection([pt1, pt2, pt3, pt4, pt5]);

// collects values from matching points into an array called 'values'
var collected = turf.collect(polyFC, ptFC, 'population', 'values');

// finds the median of those values.
collected.features.forEach(function (feature) {
  feature.properties.median = ss.median(feature.properties.values);
});

console.log(JSON.stringify(collected, null, 2));

If you were using turf-filter, turf-remove

These modules were thin wrappers around native JavaScript methods: use Array.filter instead:

var filteredFeatures = features.filter(function(feature) {
  return feature.properties.value > 10;
});

If you were using turf-jenks, turf-quantile

Use Array.map to get values, and then bring your own statistical calculation, like simple-statistics or science.js.

var values = features.map(function(feature) {
  return feature.properties.value;
});

If you were using turf-extent

turf-extent's name was changed to turf-bbox. It is functionally the same.

turf.bbox(poly) // [minx, miny, maxx, maxy]