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

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3k views

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?
54
votes
10answers
5k views

Alternatives to using Arcpy

I seem to use ESRI's Arcpy site package for virtually all of my python geoprocessing. To ESRI's credit, these are an incredible suite of tools that can help accomplish a great deal. However, I would ...
1
vote
1answer
233 views

QGIS python plugin, segmentation fault, what can I do?

I'm trying to write a python plugin to create an input file for an urban climate model out of three shape files. Unfortunatelly QGIS closes when I try to load the plugin. When I start QGIS from the ...
0
votes
1answer
116 views

How can i use ihookhelper interface in python?

I use ArcObject in python to develope a tool. I import comtypes in python to access the arcmap layers in python and use ifeaturelayer interface. I have to set featurelayer to ...
16
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5answers
2k views

How are people using Python data structures and classes in ArcPy?

This question may expose my ignorance on programming but I'm curious about how people are using different python data structures within ArcPy. This page lists the data structures in Python. I ...
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votes
2answers
2k views

How to create a map with states by attribute value?

I'm using Qgis, but I am quite familiar with R and python. So I could use any of these. I want a map of mexico but want to color the stats according to a certain variable. It goes from 0 to 100. So ...
5
votes
1answer
742 views

Create point between two points with given distance or length

What I have: Coordinates of Point A and Point C and therefore vector and azimuth from A to C What I want: Coordinates of Point B (between A and C) with a distance from A to B of 35.2 meters. ...
5
votes
2answers
258 views

Using newly created features in the next part of a python script

Good Afternoon I am trying to write a python script which buffers a large number of features from a geodatabase (but not all) and then dissolves the newly created buffer shapefiles together. ...
5
votes
1answer
2k views

How to create mask bands in GDAL and Python?

I have small program in Python that uses gdal and numpy to perform a logarithmic scale of some data into the RGB 0-255 range. Now this input data has a nodata value set to mask the valid values, and ...
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vote
0answers
424 views

Why won't this PostGIS query display in QGIS

I am having trouble rendering the following PostGIS query in qgis1.803. SELECT s.musym, st_intersection(s.the_geom,f.the_geom) as geo, nextval('"soilsplittersequence"'::regclass) as k From ...
3
votes
1answer
2k views

how to get the projection from a vectorlayer in qgis?

Hi I am trying to set the projection on a raster to match that of a vector point layer. Thus I need to findout what is the projection of a give layer, to use it in the GDAL.Dataset.SetProjection() so ...
0
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0answers
116 views

How to create a pop up attribute table for each crash located on a roadway segment in arcmap

I am trying to create a simple user interface that displays information for each crash located on the routes. I also need to display a graph along with that. I am a beginner in Python with no prior ...
0
votes
1answer
997 views

Error : keyword can't be an expression

I am getting "keyword can't be an expression" error while running the following code: >>> import arcpy >>> arcpy.MakeFeatureLayer_management("Point","P1","Layer" = 'WM-VALVE-ID') ...
2
votes
1answer
407 views

Python script for Data Driven Pages to run a series of DDP at once?

I have a several different polygon shapefiles that I am using to create individual maps for each polygon within the shapefile. The layout is the same for each map, the only thing that changes is the ...
1
vote
1answer
654 views

ogr: how to use epsg database for RD New projection?

I'm trying to assign this EPSG projection to my newly created shapefiles using ogr. The OGR Projections Tutorial says: ...any geographic coordinate system in the EPSG database can be set by it's ...
5
votes
1answer
1k views

How to Create a raster layer from a numpy array using pyqgis?

I am working on a plugin for Qgis to calculate spatial Kernel density maps. I have all the calculations working, all I am missing is a way to turn a Numpy Array, with density values into a multiband ...
10
votes
2answers
335 views

Count raster value in a bounding box (spatial extent)

I have simple question: given a bounding box, how can I count the number of specific values (say, I am interested in the number of value == 1 ) in a raster in 1) arcpy, or 2) raster package in R?
6
votes
1answer
2k views

Retrieve path and file name of current qgis project in python

Is there a way to get the path and the file name of the current project from a python script? I'm currently trying to develop a python plugin for qgis and I need to create a file with a similar name ...
3
votes
3answers
258 views

How to compare a set of images with a shapefile?

I have around 150 images (rasters), each one is just a map of certain "classes", e.g. pixel value 1=forest. I also have a shapefile that consists of roughly the same area as the 150 images constitute ...
3
votes
1answer
3k views

Writing Python script to give multiple buffers of different sizes in ArcGIS for Desktop?

I want to write a loop that will cause the output to be multiple buffer shapefiles. For example, I want a circle buffer of 50ft, 100ft, 150ft, etc. Can anyone help? I'm new to this and am trying ...
4
votes
0answers
9k views

Create a stacked bar chart with matplotlib [closed]

I'm trying to create a stacked bar chart in python with matplotlib and I can draw my bar one up the other # -*- coding: utf-8 -*- import psycopg2 import matplotlib.pyplot as plt import numpy as np # ...
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2answers
256 views

What is the difference between Geoprocessing Map object vs. MapDocument object in Python

I have the following code: mxd["C1"] = arcpy.mapping.MapDocument(os.path.join(fRoot, filename)) mxd["C2"] = [arcpy.mapping.MapDocument(os.path.join(fRoot, filename))] C1 creates a geoprocessing Map ...
3
votes
2answers
1k views

Check if field value for selected features is null using ModelBuilder

My feature class contains two fields: an identifying field U_ID, and a descriptive text field DESC. This field currently has <Null> for all features. I would like to select all the features with ...
2
votes
1answer
2k views

Mapping x, y pixel coordinates to latitude and longitudes on the WGS84 datum

Apologies in advance for the long question, I am fairly confused at this point and I figure if I show my thought process any flaws early on in the piece can be more easily pointed out. I have a grid ...
2
votes
1answer
425 views

How can I use Python to save several MXDs within the same script?

I have a program (720 lines of code) that runs multiple tasks on Arcmap .mxd files. Such as update layers, update text, add layers, etc. Within my program I have multiple "mxd.save()" instances. All ...
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vote
3answers
221 views

How can I save a column from the attribute table of a vector layer to a variable?

I am trying to write a python plugin for QGIS that can convert three vector layers into an object File for an urban climate model. Unfortunately I am stuck again with a possibly easy question: How ...
2
votes
1answer
599 views

Script for Editing TIN in Arcgis: modelbuilder works, when exported as script gives an error

Arcgis can give such a headache! I want to automate loads of small tasks, and so I need to edit empty TIN with python in order to create a full TIN. My srcript is giving errors, so I tried by hand to ...
3
votes
1answer
834 views

How to programmatically identify and rename duplicate records?

I'm trying to identify duplicate records from a field and then change these records so they become unique (eg A,B,C, or 1,2,3) and assign this to the end of the text (eg F3241 A56_A or F3241 A56_1). ...
2
votes
0answers
452 views

How to access mysql data from python built-in console?

I'm writing a QGIS Plugin, and somewhere I want to present data from a MySQL database. It's simple data(strings,etc), not Geospatial, or vector data. I'm familiar with querying databases from python ...
3
votes
1answer
187 views

Show feature classes as a checklist in a workspace in ModelBuilder

In my model, I would like to show all the feature classes inside a file gdb as a "checklist", similar to how the tool dialog window for Make Query Table looks: So instead of the input being a ...
5
votes
2answers
2k views

FWTools ogr2ogr in Python

I am trying to convert MapINFO tabs to ESRI Shapefiles using FW Tools. I downloaded the tools and can run the FW Tools Shell and convert no problem: ogr2ogr -f "ESRI Shapefile" ...
5
votes
2answers
976 views

Updating polygon geometry: deleting inner rings with python

I've searched, but can't find clear explanations how can I simply delete inner rings from existing polygons with python or extract outter rings and overwrite the geometry. Seems GDAL/OGR should be the ...
0
votes
1answer
712 views

zonal histogram fails to create output table when looping

Using python I'm having problems when trying to attempt a FOR LOOP with the ZonalHistogram function of ArcGIS 10.1. It works fine if I use it only for one image but it gives me this error while for ...
2
votes
1answer
1k views

How to drop ArcSDE connection using Python scripting?

I want to be able to control connections to ArcSDE via python. Here is my script so far using ESRI's example. import arcpy from arcpy import env env.workspace = r"SDEConnection" fcList = ...
6
votes
1answer
459 views

Python/GDAL get unique values in discrete-valued raster

I would like to get some advice on the most efficient way to return a list of unique values of a discrete-valued raster using Python and GDAL. I had thought that the most obvious way would be to ...
9
votes
2answers
2k views

How to bypass errors in arcpy for/while loop?

I have a handy script tool that loops through a workspace and renames and copies shapefiles to a feature dataset. However, if there is a corrupted shapefile somewhere in the workspace the script ...
5
votes
2answers
2k views

Is there a way to get at C's OGRLayer.Intersection() or OGRLayer.Clip() in Python?

I am working with OGR in Python and noticed that the C libraries have useful Intersection() and Clip() functions as part of the Layer class. Is there any way to get at these functions in Python? I ...
0
votes
1answer
243 views

How to populate Unique ID field after sorting?

I am trying to create an new unique id field in a feature class. I already have one field called "SITE_ID_FD", but it is historical. The format of the unique value in that field isn't what our current ...
4
votes
1answer
249 views

Dropdown menu to select vector layer from current displayed layers in qgis

I'm trying to write a python plugin to create an input file for an urban climate model out of three shape files. One of the shape files contains the buildings (polygon), one the trees (point), and the ...
6
votes
3answers
2k views

How do I extract a raster's extent in python?

I am looking for an easy way to extract a raster's extent in python. Currently, I am using gdalinfo and then parsing out the corner coordinates. The problem with this approach is that gdalinfo is ...
1
vote
1answer
2k views

Why can't I install python-qgis on Ubuntu 12?

I am with ubuntu 12 and Qgis 1.8. I have installed QGIS and grass plugin but I can't install python plugin. How to install python plugin with dependeny in Ubuntu? ~$ sudo apt-get install python-qgis ...
2
votes
0answers
105 views

How to call a method when self.iface.actionSelectRectangle().trigger() is released?

In my QGIS python plugin I use "self.iface.actionSelectRectangle().trigger()" to select features. I also have a button which changes the attributes of the selected features. Is there a way instead ...
2
votes
0answers
215 views

qgis and embedded ajax (bing map)

I need to load in a docked QWebView this html: < html > < body > < iframe width="100%" height="499" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" ...
2
votes
1answer
340 views

Is it possible to set a layer style (e.g. set the color ramp) before loading the layer using pyQGIS?

I am implementing a tool which allows an user to calculate some statistics with some data from the registration office. My question is, can I set some layer styles using pyQGIS? The analysis part is ...
0
votes
1answer
698 views

Looping Dataframe in Python doesn't Return Expected Results

I'm creating a python addin script to be used on some mxd's I have created as templates. Each map contains 2 dataframes. I need to loop through each dataframe and do some processing on each. I set my ...
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vote
3answers
509 views

Why do I get a no module error when I try to batch process in Arc10?

I was trying to batch reproject a set of shapefiles and I kept getting the error No OS Module As the set was relatively small I just did it individually, however I want to be able to batch process in ...
4
votes
1answer
1k views

How to split geometry collection into its items using Python and QGIS API?

I'm getting some geometries via intersecting lines by polygons (somewhat blindly - I don't really know if intersection exists and actually I don't need to know) using python and QGIS API: ...
6
votes
3answers
327 views

Do OSGeo4W and ArcGIS 10.0 use the same Python installation?

This question was asked several years ago at: Can ArcGIS and OSGeo4W share the same python install?, but it seems that versions have changed since then. I currently have ArcGIS 10.0 installed (not ...
11
votes
3answers
10k views

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 ...
3
votes
2answers
5k views

How do I use python to batch process the reprojection of a group of shapefiles?

My client would like his shapefiles reprojected and I would like to get a script that can batch process all the files located in the same folder. I am new to Python and ArcPy but am very interested. ...