Shapely is a BSD-licensed Python package for manipulation and analysis of planar geometric objects.

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3k views

Python Efficiency — Need suggestions about how to use OGR and Shapely in more efficient way

I'm looking for some suggestions about how to make my python code more efficient. Normally efficiency doesn't matter for me but I am now working with a text file of US locations with over 1.5 million ...
9
votes
4answers
6k views

using shapely: translating between Polygons and MultiPolygons

[EDIT: the solution to this was simply to use OGR to read shapefiles. See geographika's example.] In an ESRI shapefile, there is no distinction between Polygons and MultiPolygons. Furthermore, there ...
8
votes
1answer
1k views

Polygon overlay with Shapely

I'm trying to capture all the non-overlapping polygons indicated below using Shapely (given polygons A,B & C). Moreover, I'm hoping to do so without iteration, testing for intersect etc. The ...
8
votes
1answer
378 views

How to split two interscting polygons by the average linestring of the shared area (QGIS / python shapely)

I have two polygons, POLYGON((-5 -5,-5 5,5 5,5 -5,-5 -5)) POLYGON((1 1, 1 7, 7 7, 7 1, 1 1)) and wish to split them evenly. The result should be a split along the red marked line. I'm using ...
7
votes
1answer
531 views

Find Nearest Line Segments to Point

Background From a known Point, I require to establish the nearest surrounding "visible perimeter" against a table of MultiLineStrings, as shown on the diagram. I've searched this site with a number ...
7
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2answers
883 views

Converting KML files for use with Python library Shapely

I am trying to get a KML-file (wijken.kml) into Shapely. The KML-file is validated against the proper XML schema, so I guess the input is correct. Routes I have tried: 1) Converting to WKT or WKB ...
7
votes
1answer
394 views

Is there a significantly faster way to buffer than arcmap? [duplicate]

I hope this question is appropriate here and I apologize if it is more of a discussion question than a specific technical problem. I have to buffer 150,000 polygons for a real estate project. While ...
5
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3answers
2k views

How to write Shapely geometries to shapefiles?

Can someone demonstrate a simple way to write geometry data-structures from shapely into shapefiles? I am particularly interested in polygons with holes and linestrings. It would also be beneficial to ...
5
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2answers
835 views

Python: How to export Shapely objects to DXF file

Using shapely package for Python how to export the resulting shapely objects such as buffer to a DXF file?
5
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5answers
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Python, shapely library: is it possible to do an affine operation on shape polygon?

I am trying to create a rotated rectangle in lat/lon coordinates. Basically I have the coordinates of the center and rotation angle around the center. Is it possible to do using, shapely or gdal, or ...
5
votes
4answers
370 views

How to computational efficiently check if there are any overlapping polygons in a group of polygons?

I need to do some processing with groups of polygons. If any of the polygons in the group overlaps other polygon the result is unpredictable and don't throw any error. So, I need to detect if there is ...
5
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1answer
272 views

How do you fix Overlapping Lines?

I have a line dataset that contains some lines where the "end points" are actually found in the middle of the line. In the image below, the nodes are shown in green and one of the end points in red. ...
4
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2answers
256 views

how would one get the end points of a polyline?

I am attempting to write a script to get the end points of a series polylines, and then use those end points to create a polygon. I'm not sure which tools to begin to use on this project. I would ...
4
votes
3answers
170 views

Install Shapely with GEOS on heroku

I have a web mapping app running on Heroku. My app is written in python. Using pip I was able to install various pure python libraries that were needed. I would now like to install Shapely too. ...
4
votes
1answer
1k views

GEOS and Shapely installation on Windows

When trying to install Shapely on my Windows 64bit computer, I cannot get the GEOS library to work. So far, I have run the OSGeo4W installer from which I installed GDAL (I believe the geos library ...
4
votes
1answer
633 views

Find distance and heading from a point to a polygon in lat, lon coordinates

I have counties mapped using polygons in Shapely with latitude/longitude for coordinates. Given a complex polygon x and single point y, how would I find the shortest distance between x and y as well ...
4
votes
1answer
625 views

Wrap GEOS functionality into python

I've been looking on how to get GEOSExtractLine available in python. I looked into Shapely source to if it was available for it, but it's not. I'm trying to wrap this funcionality into Django, much ...
4
votes
1answer
450 views

Shapely unable to tell if polygon contains point

For an application I want to determine under which constituency a given coordinate falls. After looking at the various options, I decided upon shapely and fiona as the easiest way to implement this. ...
4
votes
1answer
187 views

How to generate overlapping polygons from lines output from Table To Ellipse tool?

I have a feature class of line-based ellipses generated by the Table to Ellipse tool that looks like this: What I want is polygons of the individual ellipses, however tools like Feature to Polygon ...
4
votes
1answer
406 views

How to deal with direction (CW, CCW) of circles, in particular with shapely?

I am translating an input that describes zones by mixing segments and arcs. Arcs are given by a center, 2 points (beginning/end of arc) and a direction (CW or CCW). In a first prototypes using GDAL, I ...
3
votes
2answers
104 views

Can I convert the sharp edges of a polygon easily to round edges?

I use the python module "shapely" to make Polygons (like below). Can I convert the sharp edges of a polygon easily to round edges? Such that when I have unified some polygons I could issue a command ...
3
votes
2answers
805 views

Creating Shapely MultiPolygons from shape file MultiPolygons

I'm reading a shapefile using Fiona: with fiona.open('data/boroughs/boroughs_n.shp') as source: mpolys = [p for p in source] candidate = polys[0]['geometry'] this gives me a dict containing a ...
3
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1answer
223 views

Is there an online reference available for the Fiona and Shapely libraries?

Is there an online reference available for the Fiona and Shapely libraries? I'm thinking a real reference, beside the tutorial-style documentation: http://toblerity.github.io/shapely/manual.html ...
3
votes
2answers
883 views

How to install shapely for python 2.6 (Mac) NOT 2.7?

I'm trying to use Polygonizer plugin inside QGIS, but it needs Shapely to work. I've installed Shapely (pip install Shapely) but that's for python 2.7. QGIS works with python 2.6 (on Snow Leopard) and ...
3
votes
1answer
142 views

Serialize python list containing geometry

In simple case if list doesn't contains geometry all works fine: result = [dict(f.fields, id=f.id, label=f.label) for f in features] json.dumps(result) But if result list contains geometry ...
3
votes
1answer
683 views

Does anyone have a shapely install for python “dummies” guide?

I have read both questions in regard to installing shapely on a Mac (OS Mountain Lion) and haven't been able to figure it out. I'm not familiar with python syntax and am just trying to get shapely ...
3
votes
2answers
445 views

Checking if a point is in a circle

I'm using shapely to check if a point is in a polygon, but I also need to check if a point is in a circle. Checking the docs, I don't see how do that... Maybe I could create a circle? circle = ...
3
votes
1answer
236 views

Fiona - Preffered method for defining a schema

I'm fairly new to the world of python and GIS - so this is definitely a beginner question. I am following Tom Macwrights small guide to Shapely and Fiona, and I noticed that even when opening the ...
3
votes
0answers
270 views

Importing matplotlib basemap and shapely

I'm not sure if this is the right place to ask this, but here we go. I have a python script that uses matplotlib's basemap and another part that uses shapely to do an intersection of 2 polygons. If ...
2
votes
3answers
519 views

Why is this polygon “self intersected” and invalid?

I have a polygon defined as follows: segment from 43:29:02 N 003:50:39 E to 43:34:12 N 003:43:04 E arc(CW): center (43:34:49 N 003:58:16 E) from 43:34:12 N 003:43:04 E to 43:45:45 N 003:59:56 E ...
2
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1answer
121 views

Converting Matplotlib contour objects to Shapely objects

I would like to convert a Matplotlib contour collection to a Shapely geometry collection, in order to calculate the area contained within closed contour lines. it seems that all the information is ...
2
votes
2answers
214 views

Does shapely within function identify inner holes?

I have a series of shapefiles that include both polygons and multipolygons. I am using ogr to extract them in wkb, and them I am using shapely to check if a point fall inside a polygon (or a ...
2
votes
1answer
531 views

How to install shapely on Ubuntu 12.10

I have tried to install shapely on Ubuntu 12.10. Therefore I installed libgeos-c1, pip and shapely with $ pip install Shapely. The shapely files are now in /home/user/build/Shapely. When I try to ...
2
votes
1answer
1k views

QGIS Python version

I have brewed python 2.7.3 onto my Mac (Lion), and installed shapely via pip install shapely. The Polygonizer plugin, however, does not find the shapely library. I see when QGIS loads a Python ...
2
votes
2answers
1k views

Determine if point is within an irregular polygon using Python

I would like to create a mask of a grid where points are evaluated as either 1's or 0's depending on if they lay outside of an irregular (i.e. not rectangular) polygon. I have a set of high-latitude ...
2
votes
1answer
27 views

How to get the two nearest points between two polygons

I'm trying to draw the nearest line between the nearest polygons in a Polygon dataset (ESRI Shapefile). I know that for this purpose there is the Near Tool (ArcGIS), but it just return the point TO ...
2
votes
1answer
60 views

how to differentiate between common parts of the triangle and extract linestring from it

Can you help me break down shape A to different linestrings: lines 2 & 3 AND line 1? The shape contains three different polygons (A, B, C). I wish to determine the start/end point of each part ...
1
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2answers
389 views

What is the unit the shapely length attribute?

I'm doing a very simple calculation of the length of a polyline using shapely: from shapely.geometry import LineString ... xy_list = [map(float,e) for e in xy_intm] line = LineString(xy_list) s = ...
1
vote
1answer
77 views

Equivalent function to shapely's envelope in ogr?

I wrote a very simple python function that gives me the envelope/bounding box/...based on two coordinate pairs (ower left and upper right corner): # ... def get_bounding_box(self, ll_corner, ...
1
vote
2answers
113 views

How to create a Shapely LineString from two Points

If have two points, from which I want to create a straight LineString object: from shapely.geometry import Point, LineString A = Point(0,0) B = Point(1,1) The Shapely manual for LineString states: ...
1
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1answer
59 views

Shapely WKT precision/rounding

I'm using Shapely's wkt.dumps function to get WKT from geometry objects. I can't seem to find a way to limit the precision of the coordinates. Any help is appreciated.
1
vote
1answer
96 views

create a pie shaped object in shapely and export to gis polygon object

I would like to create a pie chart-shaped polygon with concentric layers like so: I can create this simple object with: from math import sin, cos, radians from shapely.geometry import ...
1
vote
2answers
156 views

Get the vertices on a LineString either side of a Point

I have a shapely LineString and defined a shapely Point which lies along the LineString. How can I find the vertices of the LineString which lie either side of the point? (split the line in two). ...
1
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2answers
162 views

Shapely MultiPolygon Construction - Will not accept the entire set of Polygons

I am new to Shapely, so I am using a work request to learn a bit more about it. I need to execute a number of unions to build larger geometries from assessment neighborhoods in DC. I am curious ...
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2answers
298 views

Convert 3D WKT to 2D Shapely Geometry

I have the WKT of many linestrings which contains three dimensions, however my script only requires a two dimensional linestring and I therefore want to discard the third dimension. My current code, ...
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1answer
181 views

How to set the path to shapely?

I am using QGIS 1.8.0 on Mac OS 10.8.3 with python 2.7. Thanks to other threads in the forum, I have successfully installed shapely here: ...
1
vote
1answer
446 views

How do I find out if a given lat lon is in a KML Linear ring using shapely?

I'm a GIS n00b. I have some LinearRings in a KML file that give the areas for a bunch of different regions. And then I (will) have some lat lons that I want to test to see if they're in any of the ...
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0answers
45 views

Point in Polygon operation for 100G of data

I have lat/lon point locations for over a billion points, all based in the US. For each point I would like to generate a dataset that links them to their county and to their MSA according to US Census ...
1
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0answers
81 views

Fastest way to add shapely geometries to a PostGis database using geoalchemy2

I am looking for the absolute fastest approach to adding +10,000 shapely geometry objects to a PostGIS database using geoalchemy2. I'm having no speed issues when uploading to a localhost postgres ...
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0answers
126 views

How to shift vertices of shapes in shapefile using FOSS python library?

I need to shift each vertice of shape in a shapefile (of any type:point, line, polygon, multiline etc.) with Python. I need to loop in all shapes, get the vertices, get it's coordinates and for each ...