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

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How to populate an undirected graph from PostGIS?

This question is more related to resources that I might not have identified yet, although I've been searching the web for a while. In the project I'm working at the moment I need to run a ...
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3answers
831 views

Best practice in writing automated tests for QGIS plugins

I'm looking for some best practice advice on writing automatic tests for QGIS plugins written in Python. I have written tests for Python scripts in the past using PyUnit (the unittest module), but ...
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Python with GDAL and PostGIS as a replacement of ArcGIS

Few times ago, I worked with daily land surface temperature satellite images of an area with the size of Alaska. I had to process around one thousand images. I downloaded them, mosaiced, projected, ...
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2answers
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Best design for Open Source Python / PostGIS prototype

I am writing a data intensive web application that is delivered through apache. My question is about how to best arrange processing given that there are multiple options. I have at my disposal ...
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1answer
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Importing GDAL from Python window of ArcGIS for Desktop?

I am trying to run some Python code using the Python window in ArcGIS 10.1 that uses both the arcpy and gdal modules. However, when I try and import the gdal module I get an error: ImportError: No ...
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Generate near table for x number of neighbours using arcpy

There are 3 likely scenerios that I am trying to capture near distances for: An interchange subway station, which has 2 or more neighboring stations. That is, the station in question connects 2 or ...
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1answer
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How do I maintain a resposive GUI using QThread with PyQGIS

I have been developing some batch processing tools as python plugins for QGIS 1.8. I have found that while my tools are running the GUI becomes non-responsive. The general wisdom is that the work ...
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1answer
639 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 ...
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Scriptable alternative to ArcScan (particularly vectorising lines within tolerances)?

Sadly the answer to Can you access ArcScan from a python script? suggests that it is not possible to script ArcScan from within a python script. Therefore, does anyone know of any alternatives to ...
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automated georeferencing

I am attempting to fully automate the process of georeferencing a load of .png files - i have xml file containing the co-ordinates - but how can i use them? Does anyone have any advice?
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1answer
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How to prompt for user input during ArcGIS Python script tool execution?

I want to prompt for user input after all parameters have been specified for the script tool. I've seen many forum posts and stackexchange questions about this, and they all conclude that it's ...
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956 views

Arcmap Select by Attribute with Python

I would like the following to select (highlight) the "project" layer that intersects the grid, and then pull a record from the selected "Grid". I do not need to save the layer. Note: Running the ...
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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 ...
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2answers
857 views

Histogram Matching using Python to improve mosaicking process of multiple overlapping rasters?

I am trying to do histogram matching using Python to improve the mosaicking process of multiple overlapping rasters. I am basing my code on that found at: ...
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9answers
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Maximizing the use of CPU

My script is intersecting lines with polygons. It's a long process since there are more than 3000 lines and more than 500000 polygons. I executed from PyScripter: # Import import arcpy import time # ...
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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 ...
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How to create arcs between two points in Python?

I've been working on an python script automating the visualization of live point data. I have a table with two coordinate pairs. I'd like to connect these two point with an arc of a circle or similar ...
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Using variables from one Python script in other Python scripts?

I want to set up a single python file containing variables that have the locations of all my data sources. This would then be used by all my other scripts, then as a data source changes, I only have ...
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Cast arcpy result as an integer instead (arcpy.GetCount_management)

I am trying to get a number by counting how many points are in a shapefile. And this works (I think), except I then am running into trouble using that number somewhere else. Eventually, I'll be using ...
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Accessing attribute table within shapefile and replace values?

I would like to find a Python script that will access an attribute table within a shapefile and either update or replace records inside a field column. More specifically, I would like to use the ...
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5answers
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How to set all pixels with value <= 0 to “nodata” in DEM raster?

I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the ...
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How do I get the path of a project, or layer file in PyQGIS?

I am generating new raster files from vector layers on a project. I would like to save them in the same directory as the project or layer files. How do I find this path using PyQGIS?
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How does one access a featurelayer in SDE via Python?

I am trying to use Arcpy to run the CopyFeatures_management script so that I can copy a featurelayer in SDE. What do I use for the input (and output, for that matter, since I'll be copying the layer ...
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What are pros and cons of Python add-ins vs .NET add-ins to ArcGIS for Desktop?

I found in ESRI .NET help: Python All ArcGIS Desktop applications include an embedded scripting language called Python. Many areas of ArcGIS—particularly geoprocessing—are accessible through ...
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How do I use ogr2ogr to convert a GML to shapefile in Python

I am trying to convert a GML to an ESRI shapefile using ogr2ogr utility in a python script. I have successfully installed the GDAL/OGR package via osgeo but I am now struggling to find/understand ...
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Will there be a Python API for ArcGIS Server?

It seems like an obvious next step given the big push towards Python in ArcGIS Desktop at 10.0. Are there any limitations of Python compared to javascript, flex, etc that would prevent ESRI from ...
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python.multiprocessing and “FATAL ERROR (INFADI) MISSING DIRECTORY”

While trying to do multiprocessing with arcpy, I am occasionally running into this error: FATAL ERROR (INFADI) MISSING DIRECTORY I have no clue what is triggering this error, and it crashes the ...
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4answers
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Best way to find the polygons crossed by a line

I'm trying to find all the polygons crossed by a single line (a GPS track). I'm using the OGR library (from python) for computing this, but it's currently a bit 'brute-force' (and slow). For every ...
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How can I calculate the orientation of each side of a polygon in ArcGIS 10?

I want to examine the orientation of each line in a polygon so that I can calculate their solar exposure. Each polygon represents a building, and has an associated height. For the moment, I just want ...
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3answers
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Mapping between OGR and Python data types?

I'm writing a shapefile using OGR in python, creating fields on-the-fly from a python data source. Creation of a new field requires an OGR data type, is there a mapping between OGR and python data ...
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438 views

Performing a Spatial Query in a loop in PyQGIS

What I am trying to do: loop through a point shapefile and select each point that falls into a polygon. The following code is inspired by a spatial query example I found in a book: mitte_path = ...
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GDAL and Python: How to get coordinates for all cells having a specific value?

I've got an Arc/Info Binary Grid---specifically, an ArcGIS flow accumulation raster---and I'd like to identify all cells having a specific value (or in a range of values). Ultimately, I'd like a ...
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How to integrate SAGA Python Modules into ArcGIS Desktop?

I have been having a look at SAGA (http://www.saga-gis.org/en/index.html) and it seems to have some nice tools for geoprocessing. I was wondering if anyone out there has had any luck bringing SAGA ...
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How to add a toolbar via python?

Through tutorials I learned how to add a toolbutton to the plugins-toolbar via python. Now I wonder how to add a complete toolbar with toolbarbuttons via python. Can anybody give some example-code? ...
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533 views

Using ESRI geoprocessing services from a non-ESRI client (Python)?

I'm thinking it should be possible to consume an ESRI Geoprocessing service from a python script without invoking ArcPy or needing an ESRI installation on the client machine. For example I create a ...
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Joining lines when direction is not known

I am struggling with this problem. I have a polyline made up of several segments. Each segment is made up of points, each point identified in 3D space by coordinates and elevation. Together, if ...
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How to split single address field into 4 fields (House No., Direction, Name, Suffix)

I have to do some massaging of our parcel data to make it usable by a program in sheriff helicopters. The program requires one of the following address formats within the fields: Our addresses are ...
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764 views

How to create a solar intensity map for a garden plot?

I'm interested in creating a raster surface that depicts the average solar intensity per unit area for a small garden plot. I imagine the inputs into the model would be the following: Plot ...
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How do I generate thumbnails images from lots of shapefiles?

A colleague and I recently released an Open Source project called Mapoteca which is a set of Python Scripts that integrates with a GDAL/FWTools installation allowing a full walk-through of directories ...
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Calculate Date Field - today's date from datetime.date.today

I'm working on part of tool that will use arcpy.CalculateField_management to add the current date to the attribut table. I've wandered far and wide on the interwebs and can't seem to find the ...
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1answer
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Problem with setValue() function in ArcGIS 10

I'm trying to add data to an attribute table in ArcGIS 10 using the following code: def make_floor_no( shapefile ): "Makes header for number of Floors (FLO) and calculates value" fieldName = ...
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What Lidar processing tools are available in Python?

I have been using FUSION and the command line FUSION Lidar Toolkit (LTK) to process Lidar data. A broad Google search ("Lidar Python") yielded libLAS and pyLAS as Python lidar libraries, however, ...
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Unusual results for geoprocessing speed tests

I have been observing unusual performance with a Python geoprocessing script. The (attached) script performs the following actions: Use a search cursor to look up UTM zone corresponding to polygon ...
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3answers
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Python error with open layers plugin QGIS 2

I've been using QGIS for a while but since using QGIS 2 the OpenLayers plugin doesn't work for me on my home pc. (However, I have installed the same version at my workplace with success.) I have ...
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2answers
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Split a feature when intersecting with a feature of another layer using PyQGIS/Python?

I have a buffer layer (green polygon) which I want to split to two polygons whenever it crosses a barrier (blue line). I have been trying to use "splitGeometry" method, but I just can't get it to ...
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1answer
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concurrent use of in_memory workspace in arcpy

i am using a python script that's eliminating small polygons from a feature class. this script creates temporary feature classes with fixed (hardcoded) names in the "in_memory" workspace. example: ...
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How to return individual address components (city, state, etc.) from GeoPy geocoder?

I'm using GeoPy to geocode addresses to lat,lng. I would also like to extract the itemized address components (street, city, state, zip) for each address. GeoPy returns a string with the address -- ...
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4answers
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Avoiding import arcpy error (RuntimeError: NotInitialized) when using IDLE?

ArcGIS Version: ArcGIS 10, Python 2.6.5 Machine: Windows 7 64bit (Intel) I'm receiving the following error when importing arcpy using the the IDLE (gui and cmd prompt) and when using pythonwin. I ...
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562 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 ...
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1answer
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Speed of editing attributes in QGIS from a Python plugin

I'm trying to edit the value of an attribute for each feature in a layer using a QGIS Python plugin. I've found that doing this outside of editing mode is much slower than while editing (even ...