GeoJson LineString Feature Collection with holes - javascript

I have a long list of coordinates (sent by a GPS sensor) that represent the movement of an asset.
I'm using leaflet to render the GeoJSON and it works fine if I render the LineString as a single feature, but if I break it down into multiple features (inside a FeatureCollection - to apply a different dynamic color) I start to see "holes" between features.
I'm pretty sure that this is due to the fact that there is actually a "hole" in the data I'm receiving. But why it works as a single LineString feature? Is there a way to fix this?
This is an extract of the GeoJSON (very large object)
there are 3 of the 866 features of the object
{
"type":"Feature",
"properties":{
"type":"traffic",
"color":"#ffa600"
},
"geometry":{
"type":"LineString",
"coordinates":[
[
7.583125,
45.0485616
],
[
7.5830532999999996,
45.0485816
],
[
7.58299,
45.0486133
],
[
7.582893299999999,
45.0486066
],
[
7.5828682999999995,
45.04859
]
]
}
},
link to bin
https://jsbin.com/nexijajake/edit?html,output
example with single feature
https://jsbin.com/guqihajalu/1/edit?html,output


Actually, there is nothing wrong with rendering. Your data array (in your jsbin link) is an array of linestrings that are not connected with each other. You got a schema like this (imagine each row is a linestring):
[pointA-pointB-pointC]
[pointD-pointE-pointF]
In order for your line to be continuous, the last point of each linestring should exist in the next linestring as first point:
[pointA-pointB-pointC]
[pointC-pointD-pointE-pointF]
This way, your line will be continuous.
For example, the following sample (taken from your jsbin) has a gap:
const data = [
{
"type":"Feature",
"properties":{
"type":"traffic",
"color":"#ffa600"
},
"geometry":{
"type":"LineString",
"coordinates":[
[
7.583125,
45.0485616
],
[
7.5830532999999996,
45.0485816
],
[
7.58299,
45.0486133
],
[
7.582893299999999,
45.0486066
],
[
7.5828682999999995,
45.04859
]
]
}
},
{
"type":"Feature",
"properties":{
"type":"normal",
"color":"#07e36a"
},
"geometry":{
"type":"LineString",
"coordinates":[
[
7.582795,
45.0485149
],
[
7.582624999999999,
45.0483233
],
[
7.581984899999999,
45.047521599999996
]
]
}
}
];
The gap is fixed (the first point of the second linestring is the last point of the first linestring):
const data = [
{
"type":"Feature",
"properties":{
"type":"traffic",
"color":"#ffa600"
},
"geometry":{
"type":"LineString",
"coordinates":[
[
7.583125,
45.0485616
],
[
7.5830532999999996,
45.0485816
],
[
7.58299,
45.0486133
],
[
7.582893299999999,
45.0486066
],
[
7.5828682999999995,
45.04859
]
]
}
},
{
"type":"Feature",
"properties":{
"type":"normal",
"color":"#07e36a"
},
"geometry":{
"type":"LineString",
"coordinates":[
//the first point here is the last of previous linestring
[
7.5828682999999995,
45.04859
],
[
7.582795,
45.0485149
],
[
7.582624999999999,
45.0483233
],
[
7.581984899999999,
45.047521599999996
]
]
}
}
];

Related

Sort/Order List of points based on another list of points (LineString) - JavaScript

Lets say that i have a LineString (A car route):
let lineCoords = [
[ 10.964832305908203, 41.004681939880314 ],
[ 10.977363586425781, 40.99096148527727 ],
[ 10.983200073242188, 40.97075154073346 ],
[ 11.02834701538086, 40.98372150040732 ],
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];
And a another LineString (The stops that i have to make)
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[ 10.964832305908203, 41.004681939880314 ],
[ 10.994186401367188, 41.01947819666632 ],
[ 10.977363586425781, 40.99096148527727 ],
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[ 10.964832305908203, 41.004681939880314 ],
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];
Now i wanna sort arrayOfPoints based on lineCoords
How can i make it?
Can Turf help?

Javascript/json keep in database and special chars

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Such structure with attributes as text or css styles is saved into database as JSON.
To make it JSON I using json-immutable library: serialize, deserialize functions.
After save in database I provide configuration for react components as javascript variables. For example my backend generate js file with variables or small part is printing directly in html code using script tag.
Data are JSON or decoded javascript.
The biggest problem I have with save special chars.
For example if someone set ' single quote in some attribute it is saved directly.
But when I print it in html code as
var myConfig = '{anyjson}';
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Code example
https://jsfiddle.net/jaroapp/2yzud6ua/2/
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Such structure I set as parameter into ReactJS component.
If I set it as JSON and wrap in quotes then the browser throws an error. If I set it as JavaScript object into the React component I can't make ImmutableJS from this one, because this structure is read by this
https://www.npmjs.com/package/json-immutable library (I use the same to make JSON from Immutable JS to save it in database);
Thanks in advance for any hints.

I solved this problem. Short description, maybe will helpful for someone.
I get file with deserialize function form json-immutable package. And I modified function deserialize to
export function deserialize(json){
var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};
if(typeof json==='string'){
return JSON.parse(json, function(key, value, options){
return revive(key, value, options);
});
}else{
return JSON.parse(JSON.stringify(json), function(key, value, options){
return revive(key, value, options);
});
}
}
Function in package use JSON.parse for param. Maybe it's not the most elegant solution but I don't have time to find way to don't "re-json" object. Standard Object.keys and map return origin object.

How do you use d3 (v4) to map out several geoJson objects?

I have 33 geoJson objects that represent the different boroughs of London I got from this site: http://statistics.data.gov.uk/area_collection?in_collection=http%3A%2F%2Fstatistics.data.gov.uk%2Fdef%2Fgeography%2Fcollection%2FE09
Each geoJson object has the following structure:
{
"type":"Feature",
"properties":{
"gml_id":"id6268d268-5d18-4555-b9fd-fafc874cb3dc",
"LAD15CD":"E09000001",
"LAD15NM":"City of London",
"LAD15NMW":null
},
"geometry":{
"type":"MultiPolygon",
"coordinates":[
[
[
[
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51.523321274974165
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51.522821549516344
],
... and so on
]
]
]
}
}
How can I use d3 (v4) to visualise these objects as a map?
Any help is greatly appreciated!

Why can't I see the map in my browser after parsing the geojson file?

I have the huge geojson showing all the districts of Dubai. Here is a sample:
{
"type":"FeatureCollection",
"totalFeatures":224,
"features":[
{
"type":"Feature",
"id":"Community.1",
"geometry":{
"type":"MultiPolygon",
"coordinates":[
[
[
[
55.16945847438926,
25.03005371689898
],
[
55.168575711653915,
25.03074785219016
],
[
55.169258376227525,
25.03150691074316
],
[
55.169931129543535,
25.032274981961805
],
]
]
]
},
"geometry_name":"the_geom",
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"NAME_AR":"البرشاء الجنوب الخامسة",
"NAME_EN":"AL BARSHA SOUTH FIFTH",
"AREA_ID":442,
"SHAPE_AREA":2951425.95614,
"SHAPE_LEN":10871.405155
}
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{
"type":"Feature",
"id":"Community.2",
"geometry":{
"type":"MultiPolygon",
"coordinates":[
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[
[
55.34592943407097,
25.16925511754935
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55.34604885385063,
25.17297434345408
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55.34600905862783,
25.171854965446766
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55.345979182892805,
25.170726559094064
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55.34592943407097,
25.16925511754935
]
]
]
]
}
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Here is my code:
d3.json("dld.json", createMap);
function createMap(countries) {
var aProjection = d3.geo.mercator();
var geoPath = d3.geo.path().projection(aProjection);
d3.select("svg").selectAll("path").data(countries.features)
.enter()
.append("path")
.attr("d", geoPath)
.attr("class", "countries")
}
There is no error displayed in the console.
If someone could please point to me where I've mistaken, I would be the most thankful :)

The issue is, that you haven't yet set your bounding box you want to view in the map.
For this you can extend your projection like this:
var aProjection = d3.geo.mercator().scale(1000).translate([-1000, 1000]);
The entered values are just an example. Unfortunately setting this up can be quite tedious. For more information about how to find the correct values you can look here:
d3js scale, transform and translate

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