42
votes
Accepted
Welding individual line segments into one LineString using Shapely
You can use shapely's ops.linemerge to accomplish this:
from shapely import geometry, ops
# create three lines
line_a = geometry.LineString([[0,0], [1,1]])
line_b = geometry.LineString([[1,1], [1,0]]...
- 1,724
33
votes
Returning lat and long of centroid point with GeoPandas
Ran into this problem myself. If you want the x and y as separate GeoDataFrame columns, then this works nicely:
gdf["x"] = gdf.centroid.map(lambda p: p.x)
gdf["y"] = gdf.centroid.map(lambda p: p.y)
...
- 2,138
32
votes
Transforming Shapely Polygon and MultiPolygon objects
If you're using pyproj2, it's much easier to use a Transformer. Here's an example:
import pyproj
from shapely.ops import transform
project = pyproj.Transformer.from_proj(
pyproj.Proj(init='epsg:...
- 433
28
votes
Accepted
Removing small holes from the polygon
You can use the following example script. The script removes all holes from a polygon whose area is smaller than eps.
from shapely import wkt
from shapely.geometry import Polygon
# sample polygon
...
- 78k
27
votes
Accepted
Returning percentage of area of polygon intersecting another polygon using shapely
Next code:
import fiona
from shapely.geometry import shape
path1 = '/home/zeito/pyqgis_data/polygon1.shp'
path2 = '/home/zeito/pyqgis_data/polygon8.shp'
polygon1 = fiona.open(path1)
polygon8 = ...
- 30.2k
26
votes
Make shapefile from raster-bounds in Python
With shapely box and GeoPandas
import rasterio as rio
ra = rio.open("raster.tif")
bounds = ra.bounds
Convert bounds to shapely geometry
from shapely.geometry import box
geom = box(*bounds)
print(...
- 55.4k
24
votes
Accepted
Converting Polygon to MultiPolygon with Shapely?
You can wrap the polygon in a list and pass that as an argument to the MultiPolygon constructor.
Demo:
from shapely.geometry.multipolygon import MultiPolygon
from shapely import wkt
p = wkt.loads(u'...
- 1,719
24
votes
Accepted
Looking for GeoPandas QGIS equivalent of ArcGIS "Select by location" tool
If poly is a GeoDataFrame with a single geometry, extract this:
polygon = poly.geometry[0]
Then, you can use the within method to check which points are within the polygon:
points.within(polygon)
...
- 3,943
24
votes
Accepted
Shapely coordinate sequence to GeoDataFrame
Make a shapely polygon geometry from coordinate pairs.
Pass the polygon to GeoDataFrame constructor as a list.
import geopandas as gpd
from shapely.geometry import Polygon
coords = [(151....
- 78k
21
votes
Getting polygon breadth in Shapely
# create example polygon
poly = Polygon([(0, 0), (4, 0), (5, 2), (7, 5), (3, 2), (1, 3)])
# get minimum bounding box around polygon
box = poly.minimum_rotated_rectangle
# get coordinates of polygon ...
- 548
20
votes
Accepted
Calculate distance from a Point within a Polygon to its edge
Compare the point to the polygon's exterior ring:
poly.exterior.distance(point)
- 9,066
20
votes
Accepted
Plotting Shapely Multipolygon using Matplotlib
Shapely Polygon object has attribute exterior. Shapely MultiPolygon object has Polygon object sequence. You should iterate over those polygons. You can do that using attribute geoms of MultiPolygon.
...
- 78k
19
votes
Accepted
Intersecting two shape problem using geopandas
1) The problem is that the intersection of two polygons is not always a polygon
import geopandas as gp
poly1 = gp.read_file("poly_origin.shp")
poly2 = gp.read_file("poly_test.shp")
data = []
for ...
- 55.4k
19
votes
Accepted
Auto-select suitable UTM Zone based on Grid Intersection
There's the utm package, a bidirectional UTM-WGS84 converter for python.
It's able to convert a (latitude, longitude) tuple into an UTM coordinate:
import utm
utm.from_latlon(51.2, 7.5)
>>> (...
- 14.5k
18
votes
Rounding all coordinates in shapely
There are a few instances where @gene's answer does not work.
For example, the using the overprecise value -73.92391000000001
geojson = {'type': 'Polygon', 'coordinates': [[[-73.92391, 41.31064], [-...
- 656
17
votes
Accepted
Drawing ellipse with shapely
Answer
First, define a circle of radius 1.
Then define an ellipse along x and y axis.
Rotate the ellipse.
Finally, actually draw the ellipse.
Code
from matplotlib import pyplot
from shapely.geometry....
- 10.9k
16
votes
Auto-select suitable UTM Zone based on Grid Intersection
Alright, the answer from Antonio above is definitely right and pointed me in the correct direction. Here is the complete code:
# convert_wgs_to_utm function, see https://stackoverflow.com/a/40140326/...
- 714
16
votes
Accepted
Shapely polygon union results in strange artifacts of tiny, non-overlapping areas
This is typically a result of the the borders not fitting perfectly one next to another (and this is very easy to get with floating point coordinates).
As an example, I use the world dataset ...
- 3,943
15
votes
Accepted
Geopandas Line Polygon Intersection
When comparing geodataframes with geometry operations in Geopandas, the geometries are first matched by index. In the case where there is no matching index (because you only have a single polygon for ...
- 15.7k
15
votes
Snap points shapefile to line shapefile using shapely
The methodology is called linear referencing and a solution was given by Mike T in Coordinate of the closest point on a line with Shapely.
There is also a recipe in the Python Geospatial Analysis ...
- 55.4k
15
votes
Accepted
Flipping coordinates with Shapely
You can use a simple transformation function with shapely.ops' transform function.
For example:
def flip(x, y):
"""Flips the x and y coordinate values"""
return y,...
- 830
14
votes
What is unit of Shapely length attribute?
You can now use shapely w/ pyproj to get geodesic length in meters:
From: https://pyproj4.github.io/pyproj/stable/api/geod.html#pyproj.Geod.geometry_length
from pyproj import Geod
from shapely....
- 826
14
votes
Accepted
Splitting line by nearest points using GeoPandas
First make sure you union your GeoDataFrames into a MultiLineString and MultiPoint
line = gdf_line.geometry.unary_union
coords = gdf_point.geometry.unary_union
Using shapely.ops.snap and shapely.ops....
- 1,006
14
votes
Accepted
Shapely - convert polygons to lines?
bugmenot123 is ok but I find easier use the boundary of the polygons. If you have a multipolygon or a polygon with holes the boundary returns a multilinestrig, if you have a polygon without holes the ...
- 2,460
14
votes
Accepted
How to extract biggest Polygon from MultiPolygon in GeoPandas?
Here's what I would do:
max(multipolygon, key=lambda a: a.area)
The built-in max function used this way will return the item from the list where lambda a: a.area is maximized.
- 915
14
votes
Accepted
Filtering by geometry type in GeoPandas
There are many solutions (see How to filter a geodataframe by geometry type? for example)
With .loc as you but with geometry.type or geom_type
gdf0 = gdf.loc[gdf.geometry.geometry.type=='MultiPolygon']...
- 55.4k
14
votes
Is the LineString straight?
Maths should always work. You can basically test for the collinearity between the first vector of the line (i.e. composed by the two first points of the line) and all other vectors of the line (i.e. ...
- 10.9k
14
votes
Is the LineString straight?
A really simple way is to evaluate the sinuosity for each linestring, using something like this for shapely:
def sinuosity(geom):
assert geom.geom_type == "LineString", geom.geom_type
...
- 42.4k
13
votes
Accepted
Filter a GeoPandas dataframe for points within a specific country
Did you see More Efficient Spatial join in Python without QGIS, ArcGIS, PostGIS, etc and other answers on GIS SE ?
Simply
import geopandas as gpd
world = gpd.read_file(gpd.datasets.get_path('...
- 55.4k
13
votes
Interchange y, x to x, y with geopandas (python) or QGIS
shapely.ops.transform module allows passing a function to operate on coordinates. Therefore if you want to swap x, y coordinates in a GeoDataFrame you can use :
import shapely
gdf.geometry.map(lambda ...
- 241
Only top scored, non community-wiki answers of a minimum length are eligible