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

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ArcGIS problem accessing fields attribute table

I encounter a strange problem. I have a simple shape file to which I added some fields and then populated them. Now I wanna access those fields from a script to run some buffer operations. I wanna ...
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2answers
6k views

GDAL: Convert specific RGB (GeoTIFF) color to transparent

I have an RGB GeoTIFF file and I want to convert a specific RGB colour to transparent. I would like to use GDAL for doing this, but external Python scripts are also an option (though I haven't learned ...
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3answers
3k views

Check if shapefiles exists in folder

In ArcGIS modelbuilder I want to check if a shapefiles exists, if not I want to create the shapefile in that folder. I guess the calculate value tool within ArcGIS modelbuilder can be used, but I need ...
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2answers
1k views

How to truncate file geodatabase tables with python?

Everything is in the title. I need to truncate file geodatabase tables (1 or all) with python. What is the code for that? Thank you in advance!
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1answer
681 views

Using group by to set a PostGIS datasource using QGIS Python API

I am writing a QGIS Plugin and wish to obtain data from a PostGIS table using the Group By clause using something like the following code: uri = QgsDataSourceURI() uri.setConnection('localhost', ...
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1answer
759 views

How to translate ESRI cursor example to pyQgis?

For example, how to translate this code into pyqgis? rows = gp.UpdateCursor("D:/St_Johns/data.mdb/roads") row = rows.Next() while row: row.buffer_distance = row.road_type * 100 ...
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3answers
7k views

How to smooth the polygons in a contour map

Here is a contour map for which all the polygons of levels are available. Let ask how to smooth the polygons keeping all vertices preserved in their exact locations? Indeed the contour is made on ...
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5answers
3k views

Copy file geodatabase using Python?

I am trying to copy fgdb from one path to another using Python. copy(base.gdb,dest) And got the message: Error Info: [Errno 13] Permission denied: How to fix it?
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0answers
177 views

How to Auto Increment Attribute Based on Nearest Point? [closed]

An authority I am working with would like their Hydrants, a point shapefile, to be renumbered based on their location. I am looking for any python script that would help me A. Find the next closest ...
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1answer
434 views

How to move Layer to back?

from my Plugin I've loaded a rasterlayer using the following code: fileName = "/path/to/raster/file.tif" fileInfo = QFileInfo(fileName) baseName = fileInfo.baseName() rlayer = ...
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2answers
962 views

Having trouble getting specific items from a list. What am I doing wrong?

I am a total beginner when it comes to python. I received some help already getting this code started but I hit a wall. I have a directory with 200 folders, each with a geodatabase, feature dataset, ...
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1answer
646 views

Scipy: Convert RGB TIFF to grayscale TIFF and output it on Matplotlib

I want to manipulate RGB bands in a TIFF file and output the grayscale map on matplotlib. So far I have this code, but I couldn't get it on grayscale: import scipy as N import gdal import sys import ...
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2answers
3k views

Arcpy Insert Cursor not inserting all rows

Good morning all, I have a script here that takes data from a cross-tabulated non-spatial dataset where monthly values are stored in a single table row for a given year and linearizes those data so ...
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1answer
3k views

UnboundLocalError: local variable 'x' referenced before assignment

I am trying to execute this code, import osgeo.ogr def findPoints(geometry, results): for i in range(geometry.GetPointCount()): x,y,z = geometry.GetPoint(i) if results['north'] == ...
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1answer
155 views

Any reason NOT to convert to a single projection when loading GIS data?

I have been given the task of: Loading a list of properties with lat/long coordinates into a SQL Server 2008 database. Loading points and areas (polygons) of interest from a variety of shapefiles ...
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0answers
445 views

how to create shape file table from text file in QGis python

I have a text file with all field information how can create new polygon shape file table with the text file.. text file having following content.. NAME LAYER GM_TYPE KML_FOLDER ID PERIMETER ...
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0answers
994 views

arcpy spatial join input parameter problems [closed]

Using ArcGIS 10 SP4 with all extensions... I have a parent directory (J:\...\spatialjoin) containing two sub-directories of feature classes I want to spatially join. Directory 1 (target features) ...
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1answer
218 views

can't generate/display signed float values using python/gdal

I'm trying to create a raster with signed float values as the pixel values and display the results in MapWindow on windows. What is the proper gdal band type to use? I've tried both gdal.GDT_Byte ...
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0answers
124 views

refactoring an XSLT processor with minor changes

having an extremely large xml-file - which is derived from the field of geo informatics. i got it from a German subsite or the OpenStreetMap-Project: the Geograpical-Engineering-site that deilvers a ...
2
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1answer
1k views

How to use SQLite db with QGIS plugin?

Hi I would like to use SQLite for storing some information in my plugin for QGIS. I have a problem: if I put the db let say test.db among the resources as file, after compilied the resorce.qrc file, ...
4
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1answer
789 views

Raster data array output flipped on x-axis using python/gdal?

I'm trying to create a raster using the python gdal libraries and I've gotten to the point where data is being output, but the output data is flipped on the origin point's x-axis. I know I must be ...
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1answer
550 views

ImportError: cannot import name QgsVectorFieldSymbolLayer

I am using QGIS 1.7.4., downloaded April 2012, but receive an import error loading the class QgsVectorFieldSymbolLayer. As i understand this class has been added in the Python bindings on 2011-11-15. ...
3
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1answer
958 views

Select Layer by Location Produces Empty Output in Python

I am new to using Python scripts to execute ArcGIS tools. In my first script I am attempting to loop through many Select Layer by Location operations on overlapping feature classes. I want to create a ...
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0answers
181 views

Polygon symmetry detection

I was wondering if there was any way to create main axis (axis of symmetry) lines for polygons. I have polygons that represents buildings. I will want to find main axes (axis of symmetry) for those ...
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1answer
2k views

How to get size of file geodatabase feature class on disk?

Is there a simple way to determine the amount of hard drive space a feature class takes up? I feel like I'm missing something simple, but I don't recall a method that does so. You would think that ...
3
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1answer
773 views

Hyperlinking in QGIS - Add Data to current window

I am looking to add to my current action in QGIS so that a hyperlinked file will open in the current QGIS window, rather than in a new window. Here is what my action looks like: "C:/Program Files ...
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1answer
375 views

Python Field Calculation [duplicate]

Possible Duplicate: Iterative position within Field Calculator/Python I need to calculate a field for a data set that is grouped by county. At each change in county I need the column to ...
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1answer
810 views

Installing GCC correctly

I'm writing this as an utter Ubuntu newbie. I want to run the script found on Save points to a shapefile with GDAL. But I get the following error, yes this error is similar to the question posted ...
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1answer
1k views

How To Add Values to an Attribute Field Based on a Selection - Python

Alright another problem that I have. I am trying to give a priority ranking to lots based on various criteria. Basically I have 7 areas that are criteria, if lots overlap each other the criteria is ...
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1answer
242 views

Converting 2D shapefile to Equal Area Projection?

I have thousands of shapefiles with coordinates in lat/long (-180 to +180 x, -90 to +90 y), that contain polygons of which I wish to calculate the area. I'm using the Python GEOS/OGR/GDAL API. If I ...
2
votes
0answers
205 views

Setting border-style to 'no pen' using QgsGraduatedSymbolRendererV2

I am developing a QGIS plugin that, after a series of inputs, will produce a thematic map using the QgsGraduatedSymbolRendererV2. Because the polygon are very small, the boarders make it such that ...
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1answer
231 views

Python27 in Quantum GIS is missing SQL drivers in PyQT4

I am developing a QGIS plugin and need to create a table view in my GUI that I have been designing with QT Designer. I have PyQT4 installed but I have noticed that I have 2 Python directories. I have ...
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1answer
216 views

Why isn't this Python calculation working correctly?

I want to label the source files for a unified shapefile, and there are three respective columns for each. If there is no value in the column, there is no data from that source; if there is a value in ...
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1answer
4k views

How do I rotate the polygon about an anchor point using python script?

I know there would be no tool in arcpy module as such but mignt have in third party modules. I however tried taking the vertices of the polygon and moving using the below formula. but did not get the ...
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11answers
7k views

What are the Python tools/modules/add-ins crucial in GIS?

With ArcGIS 10, Python has become the de-facto scripting language for ESRI. While leading Open source software like QGIS, GeoServer, PostGIS all supports Python. Thus it became important to know/learn ...
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1answer
94 views

Other than the methods stated on the Desktop 10 Sharing Tools section, are there any other ways to distribute custom toolscripts?

Essentially I want to be able to distribute a custom script and it seems that I cannot create a .tbx file, so I looked into the other methods, but they are all only for Python modules it seems. What I ...
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1answer
625 views

Is it possible to use Python to perform network analysis on only part of a network?

I have a large network dataset and want to perform an analysis on it which would output the start/end point, the distance between them and whether they're first, second or third (etc.) nearest ...
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2answers
3k views

Point-in-polygon using Python and OGR

I want to use OGR in Python to write a simple point-in-polygon test: def point_in_polygon(point, polygon): """ point : [longitude, latitude] polygon : [(lon1, lat1), (lon2, lat2), ..., ...
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2answers
306 views

extract edge of a line of a vector layer in a new point layer [closed]

I'm using python to build a plug-in in Qgis. I need to extract the edges of each line feature of a vector layer to create a new point layer of all edges. Someone can help me? My data input is a vector ...
3
votes
2answers
208 views

How can I read the settings for the QgsPaperItem from XML?

I saved a template qpt for the map composer and now I want to read all the settings. I am able to insert the items with composition.addItemsfromXML... But this doesn't load the settings for the ...
2
votes
1answer
385 views

How to add Real Attributes to Shapefile using pyqgis?

I created the Qmarxan plugin using the fTools plugin as an example base. When I create a new shapefile using the QgsVectorFileWriter function I don't have any difficulty specifying a "Real" field with ...
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3answers
2k views

How to connect the selectionChanged signal with pyqt?

Hi I am developing a plugin for Qgis in python, I need to connect the sselectionChanged signal emitted when a feature of the layer is selected, I could not find any examples on internet, here is what ...
4
votes
5answers
678 views

Can a new point automatically be populated with data from the containing polygon

I need some help to create a script. Imagine that I'm using 3 shapes: 1 point and 2 polygons. When I create a new point I want it to assume some attributes of the polygons in which that point is ...
3
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1answer
244 views

iterating and exporting all combinations of features as shapefiles

I am trying to export individual shapefiles of all 2 pair combinations from a multi-feature polygon shapefile. To explain this better as set of FID's 0, 1, 2, 3, 4 would be exported as individual ...
4
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3answers
6k views

Add feature layer to display with in a script tool for desktop mapping 'App'

The point of this question is to find a way to programatically change the map extent based on user input. My method involves creating a Feature Layer & Selection, but if you have another ...
4
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1answer
325 views

geodjango slowness and debugging

I'm using geodjango + postgres to display polygons from tigerline on a map. Pretty simple stuff so far. My issue is that when I use the GPolygon object: django.contrib.gis.maps.google.GPolygon there ...
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3answers
2k views

Qgis Python code library documenation.

I'm looking for python documentation for specific operations in the Qgis python console. I know there is no suggestions simular to Arcpy but I would like a pure list of operation code lines as ...
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2answers
1k views

arcpy.Delete_management not deleting

I'm struggling with deleting an mxd in a for loop. My code is: import arcpy, glob, os, datetime, time from time import strftime for filename3 in glob.glob(os.path.join(folderPath, ...
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1answer
275 views

Index out of range error when cleaning up variables

I'm running a script that parses points from a flat database structure into individual feature classes with related tables. A search cursor runs through and stores each field's data in a variable ...
4
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3answers
1k views

Using threading module with Arcpy: Manager/Worker architecture

I asked this question on Stack Overflow on how to setup a manager/worker scenario. But I am getting some error when trying to use threading on my Python install with ArcGIS 10 (just the python ...