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

learn more… | top users | synonyms

1
vote
1answer
113 views

How to covert gridded (gnomonically projected by distance) data to lat/long data

I have a grid of data that is in a gnomonic projection, centered on a lat/long point (WGS-84). The grid has a 1km spacing. Given this I can easily obtain the x,y coordinates/distances from centre ...
1
vote
1answer
75 views

Calculating average of 3 fields where nulls are present

I have created a new field to calculate the average of 3 other fields in a table where nulls are present. Using python as the parser(with no code block) I used this: (!Slope_PCT! or 0 + !Flood_PCT! ...
1
vote
0answers
49 views

Running algorithm from Processing takes much much longer time than doing it from Qgis GUI

I have a road layer with 32000 features, and I want to find all the intersections. when I use processing->SAGA -> convert polygon/line vertices to points, it is all done in less than 5 seconds. ...
1
vote
1answer
175 views

Comparing Features in Python

What I am trying to do is, compare attributes in a shapefile to another updated version of that same shapefile just in a different folder. Right now I am just using the Compare Feature tool, which ...
1
vote
0answers
126 views

Batch Zonal Statistics to Spreadsheets?

I have a pretty immense amount of Zonal Statistics as Table computations to do, and would love to find a way to grab mean and variance values from the little .dbf tables ArcGIS creates and put them ...
1
vote
0answers
23 views

Is it possible to override default QGIS error messages?

From my QGIS plugin I would like to override/replace one of the the default QGIS error message ("The layer layer_url is not a valid layer and can not be added to the map") with my own message. I have ...
1
vote
1answer
60 views

Error in LineEdit when show parsing value as string

I m trying to make QGIS plugin to open xml, parse it and then show value i parse from xml to line edit, i use this code : from PyQt4 import QtCore, QtGui from ui_testparse import Ui_testparse import ...
1
vote
0answers
71 views

Programatically export labels to CAD based on another field value

The problem: I have a fairly simple procedure to export both the polyline features (architectural cad layer) and the ID's (attribute fields from polygon features that fill the rooms in another layer) ...
1
vote
0answers
320 views

Converting GRIB to Geotiff with gdal_translate in Python

I want to extract each band from a GRIB (gridded binary from http://data-portal.ecmwf.int/data/d/interim_daily/) in a single Geotiff image. I´m using Python with gdal_translate in a QGIS backround, ...
1
vote
1answer
47 views

ogr: what is the advantage of using `geom.Clone()` over `geom`?

What is the advantage of using geom.Clone() over geom? Simple example: geom = link_feat.GetGeometryRef() newfeature.SetGeometry(geom.Clone()) # or newfeature.SetGeometry(geom) ...
1
vote
1answer
94 views

How can I use pyqgis to automate a series of field calculations?

I've got a shapefile with about 30 fields that I'll need to update from time to time by importing a CSV with new data, joining it to the shapefile, and using the field calculator to carry the new ...
1
vote
0answers
158 views

Problem with polygon overlay in raster stats using gdal

I am using the raster_stats module in python to calculate the mean carbon value for different sets of polygons. Here is the code that I am using: africa_sat = ...
1
vote
1answer
102 views

Excel/Google Docs > Plss Map [closed]

Is there a way to map out PLSS (Public Land Survey System) TWP (township),RNG (range) and Section based off a field in google docs? I was thinking if you had your first column with the PLSS area in ...
1
vote
0answers
249 views

How do I smooth edges of polygons in QGIS?

Is there a built in function or plugin I can use to achieve smooth lines for my polygons instead of the blocky ones I have now?
1
vote
0answers
156 views

How can a script tool share (dynamic) variables among different modules?

I'm running a python script from the toolbox window (as a script tool). I have a second python (tkinter) module that I use as an input interface. Now, I know that the script tool can call the ...
1
vote
1answer
551 views

Null value error with Python in field calculator

I'm trying to calculate the angle between two line segments in ArcMap 10.0. I have a point shapefile, so I'm using the xy coordinates of 3 successive points to calculate the angle. I'm trying to use ...
1
vote
1answer
92 views

using arcpy to query sde database in python

I have three variables: view_name, column_name, and column_content. column_name contains id, name, address, etc. column_content contains 123, John, 200 King st, etc. user specifies the column_name ...
1
vote
1answer
344 views

Python: Ray-trace a WGS84 point with heading and distance

One of my services defines geofences for a mobile app. The geofences consists of a lat/lon pair and radius in meters, in JSON, e.g.: { "geofenceId":"geofence_b39da38cff7be4b4693cbc31b2394bbb", ...
1
vote
1answer
135 views

QGIS Custom Form: “Other” category in combo box replaced by line edit [closed]

I am trying to create a custom form for QGIS 2.0 with comboboxes containing an "other" category. I wonder how to provide a line edit to enter info replacing the "other" choice if chosen. Not sure if I ...
1
vote
0answers
116 views

model to connect points with line and set the digitize direction according to height

I'm trying to develop a tool that connects a point layer (manholes) with lines (waste water pipes) and sets the line direction according to an height attribute acording to gravity(from high to low). ...
1
vote
1answer
172 views

How to select and zoom in features from a QGIS Python Plugin

I'm very new to Python. I'm trying to find a way to select and zoom to the features from a QGIS layer. I've created a plugin and built a custom form. I have 3 values from the form which I need to ...
1
vote
0answers
259 views

Running python script outside of Arcmap's python console

My codes works fine in Arcmap's python windows. But when I try to run it in a command promt windows, It says that; ERROR 000837: The workspace is not the correct workspace type. But it works fine ...
1
vote
0answers
164 views

How to use GDAL on Heroku?

I have a geospatial python app that I want to use on Heroku. This is my requirements.txt file: Flask==0.10.1 Jinja2==2.7.2 MarkupSafe==0.19 Werkzeug==0.9.4 gunicorn==18.0 itsdangerous==0.23 ...
1
vote
0answers
302 views

Editing QGIS point layer: retrieve attributes of intersecting line layer

I'm creating a custom editing form using QGIS 2.0 and would like to modify the mouse event when creating a point. I've gotten a start by reading this thread: How to programatically check for a mouse ...
1
vote
0answers
42 views

Add a raster specifying the projection in pyqgis

I would like add an raster but I want to specify the projection. If I do : qgis.utils.iface.addRasterLayer(url,layerName) QGIS ask me to specify the projection. I want to this with python. How I ...
1
vote
1answer
54 views

GeoDjango Scale/Layers issue?

I've been having issues visualising data from a shapefile in GeoDjango using OpenStreetMaps. I believe it's some sort of a scale issue because of how it appears(as you can see in the screenshot of the ...
1
vote
0answers
43 views

Changing the symbology of layer when converting from Layer to KML using Python

Is it possible to change the symbology of a layer file using Python? I have a script that creates a layer file and converts it to kml, but every time I run it the symbology color in the kml of the ...
1
vote
0answers
74 views

Batch Clip (Editing Session)

I'm trying to correct some topology errors in my geodatabase, now focusing on two feature classes: grass and buildings. They must not overlap. However, there are plenty of spaces where the grass was ...
1
vote
0answers
181 views

PyQGIS Dialog Plugin not resetting

I have written a PostGIS search plugin that works pretty well, except two things that I just cannot figure out a solution 1) When the dialog closes and then is reopened the previous query is still in ...
1
vote
0answers
129 views

How can I draw features on GeoTIFF in Python?

I have a set of data (coords + value) and want to turn it into a heatmap in GeoTIFF. Should I calculate pixels and set them as array, or there are shortcuts? This is what I do now: driver = ...
1
vote
0answers
28 views

Able to circumvent QgsCredentials script called from Pre-execution

I've got a stored project that, when opened is connecting to my PostgreSQL DB, and is loading several layers. All good. I'm using a script that is called from Pre-execution (Processing/Options and ...
1
vote
0answers
162 views

ArcGIS Geoprocessing Service fails on data loading

I have a Desktop Script tool that works fine when run on desktop, but does not work when the results are turned into a geoprocessing serice. Running ArcGIS 10.2 on Desktop and 10.2 on server. I have ...
1
vote
0answers
645 views

How to use paths with non ASCII characters for subprocess calls with ArcGIS

I know that it is possible to create calls using unicode character encoding like \xf8 for non ASCII characters but how do I do it writing a path in a script just like: 'e:\gis\python_ø\notepad.exe' ...
1
vote
1answer
100 views

Gdalinfo and QuantumGIS does not recognize Spatial Reference even though Python does

I apply the following Spatial Reference to a file: spatialRef = osr.SpatialReference() spatialRef.ImportFromEPSG(3411) outraster.SetProjection(spatialRef.ExportToWkt() ) geotransform = ...
1
vote
0answers
36 views

How to replace accented strings in attribute tables using Python or VBA ArcGIS 10.2 [duplicate]

I need to replace accented words, into the Field Calculator, to the same non-accented ones. For example: María ---> Maria Need some help with this VB Code: Dim data as integer Dim contador Dim ...
1
vote
0answers
15 views

ArcGIS 000210 error copy to feature class [duplicate]

I have a script tool that: Creates a feature dataset within a file geodatabase Performs a Select by Attributes on a cadastral layer Copies the selected polygons into the feature dataset. The copied ...
1
vote
0answers
62 views

How to get the signal when the color changes in pyQGIS?

I would like to have the signal when the color of a vector layer is changed by the user. In the doc, there is a signal that seems to fit ...
1
vote
1answer
117 views

Creating a line along an existing polyline from a point

I have a large data set of points, all of which lie on a river network and have x, y co-ordinates. I want to calculate the slope of the river channel at each point from the underlying DEM by taking ...
1
vote
0answers
157 views

Install PyQGIS in virtualenv

Is it possible to install PyQGIS in virtual environment? I want to use rendering capabilities in my own application which runs using virtualenv.
1
vote
0answers
205 views

How to programmatically set a rule-based renderer in QGIS?

These days im in a process of developing a plugin , which highlights/change color of set of features in a vector layer depending on some calculation. i found nice article about QGIS – Rule based ...
1
vote
0answers
165 views

Kartograph - “projection not named”

The Kartograph package looks very promising, so I have been trying play around with it. As it turns out, I have been able to get the most basic map to work (the "world.json" example), but I could not ...
1
vote
1answer
85 views

How does the tolerance influence QgsGraphBuilder and tieing of points?

I am developing a script which uses OpenStreetMap data to calculate the distance (over the road network) between each building and the nearest hospital. To do this, I mainly follow the official ...
1
vote
1answer
170 views

Why does connect to Excel spreadsheet through ArcPy give ERROR 000582?

My ultimate goal is to automate kernel density analysis on xy data from a table. I am trying to learn Python but I am very new. I built a simple model to take table data and display xy data. When I ...
1
vote
0answers
86 views

header information is missing from image, after writing using opencv

I am doing complement of an image using open-cv python, while writing the image, open-cv is not writing the header information in the complemented image. my image data are in TIFF format. i am doing ...
1
vote
1answer
89 views

Python script to select a point within a cell?

I have two features: points and grid cells (vector). I want to select a point within a grid cell (some cell do not have point) using python script and create a new feature layer with below conditions: ...
1
vote
0answers
79 views

Automate data entry into Access from ArcMap

I have an Access 2007-2010 database that I'm currently working on by manually searching for roads in a defined set of areas in ArcMap 10.1 and then filling in the area's ID in an empty column in the ...
1
vote
1answer
158 views

no output file with grass:r.los

i'm using qgis 2.0 and i want to calculate a viewshed using r.los from grass tool box. after typing in the python console and a few seconds, i don't get an error message, but there is no file. the ...
1
vote
0answers
459 views

Watershed delineation; how to program

I've been trying to roll my own watershed delineation program, taking a flow direction grid and pour points as input. I coded up a quick search algorithm in Python which inspects the flow direction ...
1
vote
0answers
127 views

Where are dynamic hyperlinks stored?

A while back (ArcGIS 10.0 times, or maybe even 9.3) a colleague of mine created a mxd with a few hundred manholes and attached dynamic hyperlinks to them (pointing to photos of them). (I know this ...
1
vote
2answers
119 views

Old Windows Installers for python library fiona

Due the the recent bug as presented here for fiona 1.1, i am obliged to use a version of fiona in 1.0.x on windows 8.1. however, i can't find older versions of the installer at here. Are there any ...