Questions tagged [python]

Python is an open source interpreted programming language used in many GIS programs.

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20
votes
1answer
14k views

Replicating result of gdalwarp using gdal Python bindings

I am trying to re-project/resample with the GDAL python bindings, but am getting slightly different results compared to those from the command line utility gdalwarp. See update below for shorter ...
20
votes
2answers
7k views

Link QGIS to Anaconda Python Distribution: Spyder, iPython Notebook, pip, scikit-learn

I have Anaconda as my primary Python distro, and want to route Python related QGIS scripts through it. With Anaconda, I have Spyder, can easily install packages with pip, and can launch a iPython ...
19
votes
1answer
30k views

GDAL/Python: How do I get coordinate system name from SpatialReference?

In Python, using GDAL, I've extracted a raster's projection as a WKT string as follows: wkt = dataset.GetProjection() # wkt is 'PROJCS["GDA_1994_Transverse_Mercator",GEOGCS["GDA_1994",DATUM["GDA_1994"...
19
votes
4answers
11k views

Adding GeoPandas Dataframe to PostGIS table?

I have a simple GeoPandas Dataframe: I would like to upload this GeoDataframe to a PostGIS table. I have a Database setup with the PostGIS extension already but can't seem to add this Dataframe as a ...
19
votes
2answers
30k views

Converting projected geoTiff to WGS84 with GDAL and Python

Apologies if the following question is somewhat stupid, but I am only VERY new to this whole GIS thing. I am trying to convert some projected geoTiff images to WGS84 using gdal in python. I have ...
19
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4answers
14k views

What python web-mapping framework to use? [closed]

I am interested in developing a web-mapping application. I am relatively familiar with Python and so i'm looking for a python framework. What are my options? what are the pros and cons of each option? ...
19
votes
4answers
16k views

Is there a Python Lib for requesting WMS/WFS and saving as image/PDF?

i am wondering whether there's Python open-source GIS lib which has APIs to support call WMS/WFS from another GIS server (e.g., GeoServer) and then save the response data(WMS Basemap and WFS layer) as ...
18
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2answers
15k views

Joining (concat) list of similar dataframes in geopandas?

I have a list of dataframes, all of the same structure and all are polygons. How can I add them all together using geopandas?
18
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8answers
88k views

Installing GDAL and OGR for Python?

I am developing some code in Python, and I want to use the GDAL/OGR python bindings. What is the minimum I need to install in order to use the GDAL and OGR python bindings? What is the easiest way to ...
18
votes
2answers
11k views

Get field names of shapefiles using GDAL

I use GDAL in Python for importing shapefile. I want to know the field names for the file, my current way is: fields = [] for i in range(1, layer.GetFeature(0).GetFieldCount()): field = layer....
18
votes
3answers
9k views

geopandas spatial join extremely slow

I am using the code below to find a country (and sometimes state) for millions of GPS points. The code currently takes about one second per point, which is incredibly slow. The shapefile is 6 MB. I ...
18
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9answers
8k views

how to overlay shapefile and raster?

I have a shapefile with polygons. And I have a global raster file. I want to overlay the shapefile's polygons onto the raster grid and calculate the mean raster value for each polygon. How can I do ...
18
votes
4answers
12k views

Get all vertices of a polygon using OGR and Python

I'm having a little trouble with the Python OGR API. What I am trying to do is get all the coordinates of each vertex of the outer ring of a polygon. This is what I have so far: import osgeo.ogr ...
18
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8answers
9k views

What software to use for making digital elevation models from UAV aerial imagery?

I have a an unmanned aerial vehicle (UAV, also called a drone) and would like to use it to create a digital elevation model and orthomosaic over a smaller area (10 km2). My platform will be able to ...
18
votes
1answer
12k views

Why close a dataset in GDAL Python?

I see quite often in Python GDAL code that people close datasets at the end of their script. Why does it makes sense to close a dataset in Python GDAL? Are there any consequences if I don't do it? ...
18
votes
1answer
2k views

Calculating Focal Statistics for Special Neighborhood?

I'm looking to calculate focal statistics for each cell of a raster, within a neighborhood of a specified criteria. Background - I have three binary rasters, each representing a single vegetation ...
17
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3answers
13k views

Filter by bounding box in geopandas?

I have a geopandas dataframe in EPSG:4326 and I'd make a new dataframe consisting of all the rows that fall within a certain bounding box. First I get the bounding box that I care about (which is ...
17
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3answers
12k 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?
17
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2answers
3k views

Determining what lines have changed in updated shapefile

I'm using my county's GIS data to update the roads in OpenStreetMap. I have a copy they published last year and one that was just published, and I'd like to find all the LineStrings that have either ...
17
votes
2answers
5k views

Reprojecting WGS 1984 Web Mercator (EPSG:3857) in Python with GDAL

I am reprojecting rasters in python using GDAL. I need to project several tiffs from geographic WGS 84 coordinates to WGS 1984 Web Mercator (Auxiliary Sphere), in order to use them later in Openlayers ...
17
votes
2answers
602 views

Accessing existing instance of QGIS in stand-alone Python script

For my own data analysis pipeline, I am running a split screen setup with IPython notebooks on one side, generating variables from source data, pushing them to a CSV file which QGIS then reads/joins ...
16
votes
3answers
17k views

Generating GeoJSON with Python

I want to programmatically create a GeoJSON file using polygons from a shapefile but adding attributes from my own application. This is easily done for a shapefile: def create_data_dayer(self,...
16
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5answers
4k views

Seeking Python library (other than ArcPy) for geoprocessing such as buffer? [closed]

Excluding ArcPy, is there any python library which can do geoprocessing, such as buffer/intersect, with shapefiles?
16
votes
4answers
5k views

Python module to delete SHP features (without Desktop GIS installed)

I have a piece of software (not Arc) that runs nightly on a non-production machine which updates shapefile features from an external database. Periodically I would like to delete all of the features ...
16
votes
4answers
16k 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)) ...
16
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5answers
27k views

Difference between Vincenty and great-circle distance calculations?

Python's geopy package features two distance measurements techniques: Great Circle and Vincenty's formulae. >>> from geopy.distance import great_circle >>> from geopy.distance ...
16
votes
8answers
35k views

How to get X Y coordinates and cell value of each pixel in a raster using Python?

I'm really new to Python and I would like to know whether there is a quick method to get cell values of a raster pixel by pixel and the coordinates (map X Y coordinate of centre of each pixel) using ...
16
votes
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 ...
16
votes
2answers
12k views

How to draw polygons from the python console?

I've been visiting and revisiting the page on geometry handling in the PyQGIS Cookbook: http://documentation.qgis.org/2.0/en/docs/pyqgis_developer_cookbook/geometry.html but can't seem to figure out ...
16
votes
3answers
23k views

gdal ImportError in python on Windows

Trying to import gdal for Python 2.7.3 on Windows XP: >>> import gdal Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python27\lib\site-...
16
votes
5answers
10k views

How can I programmatically get the path of “Python.exe” used by ArcMap

I am working with an add-in of ArcMap in C#. From C# code, I have executed some Python scripts. Now, to run those script, I have hard-coded python path. But this is not portable. So, I want to get the ...
16
votes
3answers
2k views

Geotransformation for polar stereographic?

I'm currently working to import CANGRID climate data (provided as Surfer Grid ascii, ".grd" files) into ArcGIS. The grid is 95 rows by 125 columns in size.Metadata provides lat/lon of origin (lower ...
16
votes
1answer
2k views

How can I utilize NumPy arrays to optimize big data geoprocessing?

I'm interested in learning how to utilize NumPy arrays to optimize geoprocessing. Much of my work involves "big data", where geoprocessing often takes days to accomplish certain tasks. Needless to ...
15
votes
3answers
11k 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 ...
15
votes
7answers
11k views

Reading raw data into geopandas

Is it possible to read raw data into a geopandas GeoDataFrame, a la a pandas DataFrame? For example, the following works: import io import pandas as pd import requests data = requests.get("https:/...
15
votes
4answers
12k views

Weld individual line segments into one LineString using Shapely

I'm using Shapely in python and I'm given a MultiLineString with a bunch of Linestring objects. I can guarantee that all the LineString objects are simple lines with only 2 vertices and that they are ...
15
votes
4answers
8k views

Fastest way to convert big raster to polyline using R or Python?

I have a big raster file (129600 by 64800 pixel) with global water bodies (1 bit values 0 and 1) and try to extract ocean and inland water shorelines. I've tried with ArcGIS and QGIS to convert from ...
15
votes
7answers
3k views

How to implement value-by-alpha map in GIS?

I've been doing some background reading about cartograms recently and stumbled upon interesting alternative - value-by-alpha maps. Concept is described in more details here and full paper is ...
15
votes
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 ...
15
votes
3answers
7k views

Converting LAS file to numpy array?

I have begun learning how to manipulate LAS data in python and wanted to see how others handle LAS files. I would like to read the points (I am using a numpy array), and filter out classes 1 and 2 (...
15
votes
6answers
4k views

Pure Python Library for Geometry Operations

Does anyone know of a pure Python (no C or Java dependencies) library for doing geometry operations such as buffer, union, intersects, etc? I'm looking for something that is Google AppEngine ...
15
votes
3answers
1k views

Ecological geospatial conundrum

I am looking for a different, more elegant solution to a spatial statistics problem. Raw data consists of an x-y coordinate for each individual tree (i.e. converted to a point .shp file). Although ...
15
votes
2answers
9k views

Splitting shapefile per feature in Python using GDAL?

is it possible to split a shapefile per feature in python? (best would be a solution where i can temporarily save the resulting vector objects to the memory instead to disk). The reason: I want to ...
15
votes
4answers
9k views

Smoothing/reinterpolating raster with GDAL?

Short: I want to change the resolution of a raster and smooth the gray ramp like shown in the images bellow. The preference is to use GDAL, PIL or Numpy. Description: I'm kriging points into rasters ...
15
votes
5answers
25k views

No module named 'osgeo'

I have installed GDAL and checked on the command line, it is working and when I run the gdal2tiles.py on the command line it works but when I run the same file gdal2tiles.py with python IDLE, I get "...
15
votes
1answer
6k views

Clustering geographical data based on point location and associated point values

Given data points with longitude, latitude, and a third property value of this point. How can I cluster points into groups (geographical sub-regions) based on the property value? I searched by google ...
14
votes
4answers
30k views

Define Workspace for SDE Connection in Python

How do we define SDE Connection for workspace in Python Scripting?
14
votes
5answers
8k views

Recommended programming language for remote sensing?

I am beginning studies that hopefully will lead to a long career as a remote sensing specialist. I am currently working with ArcGIS for some applications and learning ENVI for others. I have ...
14
votes
2answers
16k views

Insert a Point into PostGIS using Python

What is the right way to insert a Point to a PostGIS database using Python?
14
votes
2answers
23k views

How to calculate the bounding box of a geojson object using python or javascript?

I have django app with leaflet on the frontend and I need to calculate the bbox of a geojson object so that I can pass the coordinates to map.fitBounds() I have tried some libs as well as trying the ...