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

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How to use PostGIS to handle complex geoprocessing workflows?

Our organization is considering moving our geoprocessing workflow to PostGIS. We are currently using ArcGIS, with a plethora of custom Python tools used in ModelBuilder. We're moving most of our data ...
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1answer
2k 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 ...
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1answer
7k views

How to create a script tool that will create a copy of a feature class and offset it by a given distance? (arcpy)

I want to duplicate a polygon feature class and offset all of the polygons by about 10 feet in both the x and y directions. I asked if there was any way to do this last week, and I was informed that I ...
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5answers
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How to convert line simple features to topological network?

using Gdal/ OGR is there a way to convert a shp, kml, or PostGIS line layer into a network of nodes and segments so it can be used in packages such as networkx?
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1answer
758 views

Import GRASS and SAGA modules to python script

I'm new at this. I am "building" a python plugin for qgis and I want to import modules from GRASS and SAGA but I don't understand how to do it. The plugin I want to import is Kriging interpolation ...
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1answer
165 views

How to save python session in QGIS?

After running a lot of scripts in QGIS' python console, I have more than 10 dictionaries and lists, and I need these for further analysis. Is there a way to save python session, with all these ...
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5answers
609 views

Raster diff: how to check if images have identical values?

Is there a means to check to see if any 2 given raster layers have identical content? We have a problem on our corporate shared storage volume: it's now so big that it takes over 3 days to conduct a ...
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1answer
3k 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 ...
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518 views

ArcView 3.x Avenue Bitmaps (Tabs?) vs. ArcView 10 Python Cursors

Note: While this question has an answer, any further tips for optimizing a cursor process would be greatly appreciated. I will be monitoring for any updates. Currently, my boss (who works in Avenue) ...
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2answers
3k views

Measuring distance in spherical Mercator vs zoned UTM

I've got points in WGS84 lat/long and I'd like to measure "small" (less than say 5km) distances between them. I can use the haversine formula from http://www.movable-type.co.uk/scripts/latlong.html ...
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702 views

Can ArcGIS and OSGeo4W share the same python install?

I don't like unnecessary duplication. Is it possible to install python only once and have both ArcGIS and OSGeo4W use it?
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3answers
267 views

Setting symbol descriptions of ArcMap layout legends from table?

ArcMap has the ability to show an extended description for each item in the symbol list. How can I populate that property from a table? The goal is to avoid having to edit each symbol one by one in ...
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2answers
767 views

Python, GDAL and building raster attribute tables

I have an integer raster for which I would like to build a raster attribute table using Python and GDAL. I can create a GDAL raster attribute table in Python as follows: >>> rat = ...
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2answers
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Error handling with python script in ArcGIS 10

I have a python script that I am using to create a list of all mxd files (with full pathing) in our Projects folder. The script then uses that to iterate through the list and do a ...
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2answers
1k views

Inserting newlines in Rectangle Text elements via ArcPy causes overlap?

I ran across an issue the other day when I tried to use ArcPython's mapping module to edit rectangle text elements with newlines (\n) in an ArcMap document. Here's what the output looked like: ...
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1answer
501 views

Is there a way to properly have GDAL raise exceptions in Python?

I am working with GDAL in Python and have wanted to get GDAL to raise exceptions so that I can do something useful with them. For instance if a file cannot be opened with gdal.Open() I would like to ...
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ArcGIS Python Tool - Importing Custom Script Into ToolValidator Class

I had posted a question last week about customizing a ToolValidator class and got some very good answers. In working with the proposed solutions, I have created a custom module that performs queries ...
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4answers
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Bilinear interpolation of point data on a raster in Python?

I have a raster that I'd like to do some point interpolations with. Here is where I'm at: from osgeo import gdal from numpy import array # Read raster source = gdal.Open('my_raster.tif') nx, ny = ...
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When iterating over a vector layer with pyqgis, how do I check whether a feature is selected?

While iterating over a vector layer using the following code (summerized from the example in the pyqgis cookbook), is there a way to check whether a feature is selected? provider = ...
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2answers
865 views

GeoTIFFs made in GDAL don't have min/max range when loaded in Arc/QGIS

I'm creating some floating point rasters in GDAL with the GeoTIFF driver. When I load the resulting images into QGIS or Arc the default symbology puts the min at -3.40282e38 and max to 3.40282e38, so ...
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3answers
1k views

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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1answer
385 views

Is there a way to use ArcPy and PyGRASS tools in the same Python script?

I´m trying to write a Python script, that includes different ArcPy / ArcGIS commands and want to combine it with GRASS geoprocessing tools. Unfortunately importing the GRASS libraries doesn´t work. ...
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2answers
473 views

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
1k views

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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532 views

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
1k views

Arcobjects in Python: assign interface to objects with feature (shape) geometry

I am trying to use ArcObject in Python. I do have problem with assigning an interface (i.e. IZ.InterpolateZsBetween) to my object with geometry data, code is: from Comtypes.client import ...
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740 views

Scriptable alternative to ArcScan (particularly vectorising lines within tolerances)

Sadly the answer to this question suggests that it is not possible to script ArcScan from within a python script. Therefore, does anyone know of any alternatives to ArcScan (either within ArcGIS, or ...
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344 views

Can ArcGIS ModelBuilder open Excel file for manual editing, then feed those edits back into model?

I have been tasked with creating a model using ArcGIS ModelBuilder, that initially runs a couple of geoprocessing tasks, before then joining an Excel table to the result of those geoprocesses. ...
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1answer
976 views

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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1answer
755 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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307 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 ...
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3k views

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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Define Workspace for SDE Connection in Python

How do we define SDE Connection for workspace in Python Scripting?
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How do I use 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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287 views

Subset Folder Contents ArcPy

I have about 1500 .txt files within a folder named 3410001ne => 3809962sw. I need to subset about 470 of these files to process with a Python script. Below is the section of code prior to my for ...
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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 ...
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How to round a column in attribute table (ArcMap)

I want to use the Field Calculator in ArcMap to round an existing column to two decimals. Currently I have a column that is 6 decimal places long and would like to simply round it down to 2 decimals. ...
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2answers
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How to access Esri ArcPy modules from Enthought Canopy?

I have ArcGIS 10.1 running on my windows system and I have also installed the new 32-bit Canopy Express Enthought Python Distribution. Is it possible to load and use the Esri ArcPy modules from ...
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3answers
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How to find the locations of the highest values in a raster?

Using ArcGIS 10, I have a raster where I would like to find the pixel with the maximum value in the raster and return its location (center of pixel) in decimal degrees. I would like to iterate through ...
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2answers
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Finding mid-point of line using ArcPy?

How can the mid-point of a polyline be calculated using the geoprocessing framework, e.g. in a Python script? The polyline.centroid property returns The true centroid if it is within or on the ...
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2answers
509 views

How to add different sized rasters in GDAL so the result is only in the intersected region

I'm writing a Python method that adds two rasters and generates a single raster output. For reasons beyond my control, the extents of the input rasters are different, but they do overlap. Is it ...
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5answers
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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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3answers
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How to fully load a raster into a numpy array?

I have been trying to check my filters on DEM raster for pattern recognition and it is always resulting in missing last rows and columns(like..20). I have tried with PIL library, image load. Then with ...
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How to Remove return/newline (\n) character from Field using Python and Field Calculator?

I have a geodatabase table with a field that I'm trying to remove return characters (new line). I found this post (How can I remove (chomp) a newline in Python?) of how to do it, however it is not ...
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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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Is there a 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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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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2answers
899 views

ArcMap running scripts slower if you import Arcpy

I am finding ArcMap runs slower, if you have written a script, which imports arcpy. You may wish to write a script that can be operated in ArcMap, through the python window, or as a standalone ...
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How to create a button in Arcmap 10 to run a Python program?

I have a script that I want to run within ArcMap when a button in a toolbar is clicked, and so far I have only been able to make the script into a script tool. I need it to run as a command, not as a ...
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1answer
642 views

Fastest methods for modifying attribute tables with Python?

A while ago, I wrote a quick Python function for converting an attribute table to a python dictionary, where the key is taken from a user-specified unique ID field (typically the OID field). ...