Turfjs/turf

A modular GIS engine written in JavaScript

Deleema Fernando

@delleemarf_twitter

Hey all, Im looking for answer for this question https://stackoverflow.com/questions/49645333/turfjs-linesplit-not-working-properly-when-splitter-is-near-vertex-point
I really need a help at the moment.

Thanks in advanced

Ohad

@osadan

anyone now's when turf plans to release 6.0

Andy Prasetya

@YggdrasilX_twitter

Hi all. I need to count how many occurences (point) in a set of polygons by remarking the each occurences property in polygon.
The polygon is:

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "id": 0,
            "properties": {
                "id": 1,
        "occurences": 0
            },
            "geometry": {
                "type": "Polygon",
                "coordinates": [
                    [
                        [
                            109.914952,
                            -7.19584
                        ],
                        [... about 50.000 nodes ...] 
                    ]
                ]
            }
        },
                [... less than 100 polygons ...]
        ]
}

and the points:

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "id": 0,
            "properties": {
                "id": 1
            },
            "geometry": {
                "type": "Point",
                "coordinates": [
                    109.912194,
                    -7.711743
                ]
            }
        },
                [... about 20.000 points ...]
        ]
}

In Turf.js, I believe I can do it with pointsWithinPolygon or booleanPointInPolygon. My questions are: which is faster/efficient? How to do it?
Much obliged for your attention.

Arsen Stahanov

@ArStah

Hey guys

Can someone tell me is it possible to do with turf something like turf.along but opposite, i mean, i have a line, and 2 points on it, i need to get the distance between these points?

almandarin

@almandarin

Hi there, thanks for the great work, though I don't get the squareGrid:
var squarebin = squareGrid([0,0,2,2], 1, {units: 'degrees'});
Gives me {"type":"FeatureCollection","features":[{"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[[0.49941580254182905,0.49941580254182905],[0.49941580254182905,1.500584197458171],[1.500584197458171,1.500584197458171],[1.500584197458171,0.49941580254182905],[0.49941580254182905,0.49941580254182905]]]}}]}

Why it does not give me four Features starting from 0,0? Am I missing something?

Kevin Yanuk

@fugwenna

has anyone here attempted to find a destination point with a back bearing using: https://www.movable-type.co.uk/scripts/latlong.html

Rusty Green

@rustygreen

Can anyone suggest a turf function (or series of operations) to accomplish the image above?

Alex

@apgeo

one (generic) option is to test for each point in the linestring if it is contained in one of the polygons, then to construct the ouput multilinestring from the positive ones (points)

Rusty Green

@rustygreen

Currently I'm using lineIntersect and then splitting the line based on the intersecting points - but it seems like a lot of extra overhead - figured this was a common scenario

16AGR-Durham

@16AGR-Durham

I don't know how to look at forum history, so will ask a question that I am sure has been asked many times (a) does turf.bearing(point1, point2); return true or magnetic and if true (b) is there a function to convert true to magnetic based on declination in the long/lat input?

I think it returns true

Kevin Yanuk

@fugwenna

@16AGR-Durham i believe the bearing code was derived from this: https://www.movable-type.co.uk/scripts/latlong.html

Matthias Tylkowski

@tylkomat

All the maps on the turf page are broken. Seems someone messed up the css.

Per Liedman

@perliedman

@tylkomat they look ok here. do you have a URL that is not working for you?

Matthias Tylkowski

@tylkomat

@perliedman That's funny, now they are fine. Maybe mapbox messed up their own css

Matthias Tylkowski

@tylkomat

What can I use to reverse the result of difference? union?

xlcrr

@xlcrr

Thought ye might be interested in this :D https://openlittermap.com/maps/The%20Netherlands/Zuid-Holland/Wassenaar/map

Want to download the data? Alright cool https://openlittermap.com/maps/The%20Netherlands/Zuid-Holland/Wassenaar/download

John de Stigter

@rjdestigter

Is booleanPointInPolygon supposed to return true even if a given point resides within a hole of a given feature?

John de Stigter

@rjdestigter

(never mind, looks like I ran into some bad spatial data with incorrect rotation)

Matthias Tylkowski

@tylkomat

Hello everyone. Does anyone know how I can create a bounding box that is rotated by a custom amount of degrees?

Gabriel Cuenca

@Gcuencam

Hello ! Is there any way to calculate the route between two points without going through a certain area using turf and mapbox?

Morgan Herlocker

@morganherlocker

Hey @Gcuencam! I would recommend requesting a route for your waypoints from the Mapbox Directions API, using the geojson flag, for simplicity (default is polyline encoding). https://www.mapbox.com/api-documentation/#retrieve-directions

then run the result against turf.length, which measures the distance of a linestring

Morgan Herlocker

@morganherlocker

@tylkomat bit late to your question, but you can combine turf.bboxPolygon and turf.transformRotate to achieve this

Matthias Tylkowski

@tylkomat

@morganherlocker No worries and thank you. In the meantime I came to the same solution.

Mireille Raad

@migheille_twitter

hey! just a small question - can turfjs be used to work with files in the 200M rows scale ?

i've done some work where I take location data, create hexbins and calculate how many points are in a bin

I worry I might run into buffer errors

so i was just wondering, should I use turfjs for this scale of data or look for something else ?

ohenepee

@ohenepee

Hello... is there anyway to get the cardinal corners of a bbox, like northeast, northwest, southeast, southwest?

David Haynes

@dahaynes

Hello, Has anyone tried to use Turfjs with MongoDB? I'm looking for a bit of assistance in performing centroid queries on a collection of boundaries

Pochivalin Alexey

@pochivalin-alexey

Hello, can you help me? How update feature coordinates using turf.coordReduce? What is the difference turf.coordReduce and turf.coordEach?

Pochivalin Alexey

@pochivalin-alexey

@ohenepee may be extract vertexes from bbox and use turf.bearing . . .

RISHAV ROY

@rishavroy1264bitmesra

How to project a point over linestring using turf ?

Morgan Herlocker

@morganherlocker

turf.along will give you a point N distance along a linestring

Dan Ford

@danford1

Hey all, I have a vector tile polygon source hosted in Mapbox Studio and an isochrone geojson generated using the isochrone api. I'm trying to use turf intersect to find a count of polygons within the isochrone, but getting Unknown GeoJSON type: undefined because one of the data inputs is vector tiles. I found a question on this back in 2016, but looking for a current answer/resource that will help me learn a) whether I need to convert the vt to geojson and b) best method for doing this client side. Maybe the best answer is to just use a geojson source to begin with?

Pochivalin Alexey

@pochivalin-alexey

@danford1 Attention, turf intesect using only two polygon. Simple way to convert vt geometry to geojson format use turf.polygon method.

Dan Ford

@danford1

OK, thanks! I just realized that I have to iterate over each polygon in the feature class and run a separate intersect. Does anyone have an example of this they can share with me?

Pochivalin Alexey

@pochivalin-alexey

@danford1 What example are you interested in?

Dan Ford

@danford1

How to run an intersect between Poly1 and a feature class with many polygons.

Ilya Radchenko

@knownasilya

Is there a way to do an intersect and also handle donut holes?

Has anyone done something like this?

Pochivalin Alexey

@pochivalin-alexey

@knownasilya By geojson spec polygon without hole like this:
{ "type": "Polygon",
"coordinates": [
[ [100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0] ]
]
}
and with hole:
{ "type": "Polygon",
"coordinates": [
[ [100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0] ],
[ [100.2, 0.2], [100.8, 0.2], [100.8, 0.8], [100.2, 0.8], [100.2, 0.2] ]
]
}
Attention: first array is bigest area
Check this two condition and do intersect.

Ilya Radchenko

@knownasilya

Thanks @pochivalin-alexey

Ben Boughton

@benboughton1

Hi can anyone help as to why this dissolve example is not dissolving? http://jsfiddle.net/dejz01v4/1/

Ben Boughton

@benboughton1

I put the question on StackExchange if anyone would like to answer there - thanks!

https://gis.stackexchange.com/questions/367647/turfjs-dissolve-not-working-as-expected

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