Questions tagged [shapely]

Shapely is an open source Python package for construction and analysis of 2D planar geometric objects common to geographic information systems.

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32
votes
5answers
50k 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 ...
15
votes
3answers
55k views

Check if a point falls within a multipolygon with Python

I have tried several examples of code using libraries such as shapefile, fiona, and ogr to attempt to check whether a point (x, y) falls within the boundaries of a multipolygon created with ArcMap (...
16
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3answers
12k views

Dissolving polygons based on attributes with Python (shapely, fiona)?

I have been trying to create a function that does basically the same thing that the QGIS "dissolve" function. I thought it would be super easy but well apparently not. So from what I have gathered ...
4
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2answers
11k views

Intersect Shapefiles using Shapely

What I'd like to try and do is intersect some point buffers with census tracts, maintain their ID's and the tracts attributes. I found a sample from http://www.macwright.org/2012/10/31/gis-with-...
20
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2answers
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How to polygonize raster to shapely polygons

I am seeking an open-source python solution to convert raster to polygon (no ArcPy). I did know the GDAL function to convert raster to polygon, and here is the manual: http://pcjericks.github.io/py-...
7
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2answers
12k views

Intersecting two shapefiles from Python or command line?

I'm new to working with geo data and trying to address a similar question to the one posted as How to calculate the size of a particular area below a buffer in QGIS Using command line and/or shapely/...
2
votes
1answer
4k views

Setting 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 console,...
31
votes
3answers
23k views

Transforming Shapely Polygon and MultiPolygon objects

Is there an easy way of transforming Shapely objects (namely, Polygons and MultiPolygons) from one projection to another without having to dig around and extract coordinates by hand? In fact, I don'...
9
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3answers
6k views

Removing small polygon gaps in Shapely polygon?

I know this issue has been addressed before with different software, but how do I do it with Shapely? I have a polygon with a very small gap on the interior of the shape: Here is a close up: The ...
7
votes
2answers
21k views

Convert shapely polygon coordinates

I am trying to work with a shapefile using shapely, fiona and python. The original coordinate system is in latitude and longitude that I am trying to convert to state plane system. So I want an ...
4
votes
1answer
6k 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 ...
18
votes
1answer
8k views

Finding Nearest Line Segments to Point using shapely?

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 ...
12
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2answers
18k views

What is unit of 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 = '%...
5
votes
4answers
7k views

Rounding all coordinates in shapely?

Following on from How can I add points to a LineString in shapely?, I'm hitting a problem where floating point representations mean objects aren't precisely where I expect them be after they are moved ...
1
vote
1answer
3k views

Writing a shapefile using OGR, from Shapely Geometry - No feature added Error

I am trying to write a shapefile from a Shapely geometry using PyQGIS in the QGIS 2.6.0 console. Lines of code before the OGR method to write shapefile: extnt = poly.extent() # gives a QtRectangle ...
3
votes
1answer
9k views

How to find the intersection areas of overlapping buffer zones in single shapefile?

Find the intersections of the buffer zones I found an example where they tried finding the intersection of two different shapefiles -Intersect Shapefiles using Shapely. I've tried to adapt my code to ...
3
votes
1answer
1k views

Computing convex hull of points using shapely

I have a points shapefile and I want to compute the convex hull of the points using shapely, and output the result as a shapefile using Fiona. Does anyone know how I can do that? This is what I have ...
4
votes
2answers
2k 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 ...
20
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2answers
20k views

Getting polygon areas using geopandas?

Given a geopandas GeoDataFrame containing a series of polygons, I would like to get the area in km sq of each feature in my list. This is a pretty common problem, and the usual suggested solution in ...
15
votes
3answers
12k views

Understanding use of spatial indexes with RTree?

I'm having trouble understanding the use of spatial indexes with RTree. Example: I have 300 buffered points, and I need to know each buffer's intersection area with a polygon shapefile. The polygon ...
11
votes
2answers
26k views

Creating 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: A ...
18
votes
3answers
13k views

What units are used by GeoPandas/Shapely area and distance functions?

it looks like a silly question, yet I can't find clear answer on that: what units geopandas/shapely use calculating distance/area between objects?
12
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5answers
5k views

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, ...
6
votes
1answer
12k views

Split lines at points using Shapely

I'm trying to split a shapefile of geometry type 'line' at a shapefile of geometry type 'point. These points are snapped to the lines and are the start points/end points of other line shapefiles. ...
2
votes
1answer
4k 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, ...
15
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2answers
8k 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 ...
17
votes
5answers
17k views

Area in KM from Polygon of coordinates

I have polygons from coordinates in (python shapely) that looks like this POLYGON ((24.8085317 46.8512821, 24.7986952 46.8574619, 24.8088238 46.8664741, 24.8155239 46.8576335, 24.8085317 46.8512821)) ...
7
votes
1answer
24k 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. ...
9
votes
1answer
14k views

Turning GeoDataFrame of x,y coordinates into Linestrings using GROUPBY?

I have a dataframe of X,Y coordinates that represent points along the paths taken by several different entities. Pseudo-data here, but it is roughly of the form: entity_id lat lon time 1001 ...
7
votes
3answers
10k 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 ...
7
votes
2answers
4k 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 ...
5
votes
1answer
11k views

Intersecting two shape problem using geopandas

I'm trying to intersect two polygons based on the following link, intersecting two shapefiles from Python or command line But problem occured that shows a "ValueError: Geometry column cannot contain ...
4
votes
1answer
8k views

Assign a point to polygon using pandas and shapely

I have a series of Easting and Northing coordinates in pandas dataframe along with other columns of information. I know the coordinates fall within and administrative area and want to match the ...
10
votes
1answer
5k views

Returning percentage of area of polygon intersecting another polygon using shapely [closed]

Using the shapely library, suppose I have a shp file V and another shp file Z. For each polygon v in V, and for each polygon z in Z, I would like to know what percentage of the area of z falls within (...
8
votes
2answers
8k 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 ...
6
votes
2answers
11k views

Creating a circle with radius in metres

I am using shapely and Python. How should I go about creating a circle using shapely whose radius is in meters? If i use sampleCircle = Point(1,1).buffer(1) print sampleCircle.area This returns ...
9
votes
1answer
11k views

Line vs. Polygon Intersection Coordinates

I am working with Python, Shapely and Fiona... Is there any way where I can give in an input of a line shapefile and a polygon shapefile, and get a result of the intersection points and their ...
8
votes
2answers
10k 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 ...
5
votes
2answers
5k views

Auto-select suitable UTM Zone based on Grid Intersection

I was wondering if the following approach a) would be considered valid and b) someone already did this in python. I have a python script where users can choose an area of analysis (anywhere on the ...
5
votes
1answer
6k views

How to efficiently determine which of thousands of polygons intersect with a linestring [duplicate]

I have a shapefile that contains several thousand Polygons/MultiPolygons and another shapefile that has a variable number of LineStrings. In the example below the blue Polygons are those that ...
4
votes
1answer
4k views

Shapely/ Python looping through a number of polygons

I am trying to loop through a set of polygons in shapely so using python) to determine whether they overlap or not. I do not want to do it manually as later i want to generalise the procedure and do ...
3
votes
1answer
1k 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 ...
1
vote
0answers
2k views

Generate random points in polygon. Algorithm question

i created a Random Point Generator in python using the algorithm described here by @whuber. The algorithm is implemented using Shapely, PostGIS and psycopg2. To boost performance pythons ...
30
votes
2answers
6k views

Using OGR and Shapely more efficiently? [closed]

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 ...
12
votes
4answers
16k 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 ...
28
votes
4answers
59k views

Shapely not installing correctly

I am trying to run Shapely on a new machine, and tried both installing it from source, using the installer on its webpage, and using pip install shapely. Every reference I try to make from the library ...
12
votes
2answers
17k views

Creating Shapely MultiPolygons from shapefile 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 ...
8
votes
2answers
6k views

Drawing ellipse with shapely?

How do I draw an ellipse with shapely?
4
votes
2answers
23k views

How to measure distance using shapely

Reading the documentation...it looks like I should have this right, but I don't. The example is: Point(0,0).distance(Point(1,1)) 1.4142135623730951 Based on this example I wrote this block (....
3
votes
1answer
6k views

Finding differences between two shapefiles in Python

I'm trying to find out whether there were any border changes between two yearly shapefiles. I've heard a lot of praise for Python's open source GIS tools like Shapely/Fiona, and thought I would try ...