Questions tagged [python]
Python is an open source interpreted programming language used in many GIS programs.
1,435
questions with no upvoted or accepted answers
11
votes
0answers
460 views
Alter Minimum Bounding Box Algorithm
I'm trying to create an algorithm similar to minimum bounding box (though it may end up looking nothing like it). In this case the angle will be passed as a parameter and given the angle I need the ...
9
votes
0answers
398 views
Accessing existing instance of QGIS from stand-alone python script
For my own data analysis pipeline, I am running a split screen setup with iPython notebooks on one side, generating variables from source data, pushing them to a CSV file which QGIS then reads/joins ...
8
votes
0answers
321 views
Executing bidirectional dijkstra on TIFF image?
Can anyone indicate an example of how to do this? Link, tutorial etc...
I started a discussion here about how to load a TIFF image like a graph nicely answered by @sehe.
But, in this post the image is ...
8
votes
2answers
3k views
Login to USGS Earth Explorer and download Landsat imagery with Python
I want to login to the USGS Earth Explorer website at http://earthexplorer.usgs.gov/ with Python and download imagery from the Landsat Archive collection just by giving it username,password,path/row (...
7
votes
0answers
77 views
Coarse Woody Debris extraction
I created very high dense point cloud of some forest plots using terrestrial laser scanner. Then removed points above 1.3 meter to see the coarse woody debris (Fallen dead trees). Attached is the ...
7
votes
0answers
221 views
Multithreaded DB connection for QGIS plugin
I am using QGIS 2.18.21 and PostgreSQL 9.6. on a Windows 8 machine.
I am trying to do processing of a certain database task in the background, and I want the user to be able to continue to work in ...
7
votes
0answers
189 views
Computing the horizon profile given a DEM in python
Can anybody orient me towards an open source python script that computes the 360° horizon profile (azi + elevation of highest topography in eye sight) from a single point (x,y,z) on Earth (account for ...
6
votes
0answers
278 views
MapScript with Python 3
I am trying to build raster summarizing features into a GeoDjango webmap,
and would like to use the django-raster and django-wms packages to do so. I believe that I have them set up correctly, but am ...
6
votes
0answers
233 views
Different results from GDAL raster attribute table command on mac and windows
I am trying to get the raster attribute table of the following file:
Shift_cult_past_current_prediction_20160107_gr1DD.tif available here: https://www.dropbox.com/s/fmomfpro3j6dmz8/...
5
votes
1answer
353 views
Geoalchemy: insert 3D elements in PostGIS database
I have shp files that I would like to insert into a PostGIS database. I'm planning to use Geoalchemy2 and geopandas to do so. However, my data have the geometry types LINESTRING Z and POINT Z. As I ...
5
votes
2answers
147 views
Automatically moving along columns within a layer as moved to the next item in a QGIS Atlas?
My problem is quite hard to explain, I have attached some images to help illustrate my issue.
I want to produce a large number of maps which overlap in geographic area. Currently my data is arranged ...
5
votes
0answers
145 views
Determining Bounding Points of UAV Images
I know the EXIF data from drones contains the GPS point central to the photo to provide photo location. What I'd like is to determine the lat/lon of the four corners of the image. I've done a pretty ...
5
votes
1answer
377 views
Competing versions of GDAL
This is confusing, and a question I've harvested from a duplicate, so let me start with my setup.
OS: Windows 7 x64
GIS Client 1: ArcGIS Desktop 10.5
GIS Client 2: ArcGIS Pro 1.4
GIS Client 3: ...
5
votes
0answers
642 views
Setting band names when writing multiple layer rasters using GDAL with Python?
I want to write a raster file (using GDAL+Python) with multiply bands. However, I do not know how to named bands. Their names are always "Band 1", "Band 2", etc. I search and found a function that ...
5
votes
0answers
2k views
gdal/python: tif not recognised a supported file format
I'm trying to open a tif using gdal, read it as a array, do some math, and write it back as a tif.
However, when I try to gdal.Open(tif) in python, I get the error:
RuntimeError: /att/gpfsfs/...
5
votes
0answers
1k views
Speed up row-wise point in polygon with Geopandas
I have a geopandas GeoDataframe which contains some attributes and a geometry column which is filled with shapely Point(lon, lat) objects. Moreover, there is a GeoSeries which is equally indexed as ...
5
votes
0answers
860 views
library for minimum bounding box “by width” in javascript or python
I'm looking for a library (or at least a code snippet) to calculate the minimum bounding box "by width" in javascript or python. Below is an illustration from the ArcGIS documentation of that ...
5
votes
0answers
875 views
Print Composer Template produces empty map?
I have a print composer template which I'm trying to populate with different subset queries from a CSV-derived vector layer using the Python API. However, all the output PDFs contain everything except ...
5
votes
1answer
325 views
Displacement when clip raster by shapefile
I run a script to clip raster by shapefile. Even with layers own the same crs (epsg: 4674) the output raster be displaced. I didn't find out in my script what is caused the error.
Here is my code:
""...
4
votes
1answer
57 views
Adding up several rasters to show the change
I want to add several images such that their change is shown in different colors. Such as the following in which I simply added two images in their grayscale. But I would like to have a colored ...
4
votes
0answers
37 views
Randomized organic warp of adjacent polygons that preserves topology and fixed nodes
I'm looking for algoritms to modify a set of polygons to make them appear more organic. They still need to maintain their topology and furthermore some of the nodes might be fixed. Please see the ...
4
votes
0answers
229 views
QGIS 3 Python plugin psycopg2 Postgres Notify/Listen Live Connection
I'm developing a plugin for QGIS3 for my company, where my managers can allocate tasks to other users. I have programmed two tables within the python script, witch will be only visible according to ...
4
votes
0answers
100 views
Variable width buffer based on axis directions in QGIS
I need to buffer a polygon with a different distance in the x and y directions.
I should add that my polygon has the following properties:
closed (obviously)
simple (no edge crossing, no more ...
4
votes
0answers
104 views
Speed execution of PyQGIS algorithms
I don't understand why if I do "manually" some algorithms I get results much faster than when I insert the same in a pyqgis code (with the same input).
This happens, for example, with the extract ...
4
votes
0answers
103 views
Performance improvement methods in a shapely environment
I am trying to use the Shapely and Fiona libraries to eliminate polygons from one layer (some triangles) from another layer (which represents the world's oceans).
I am looking for suggestions to ...
4
votes
0answers
227 views
Installing third party python library in QGIS 2.18.x Windows
We are running into a strange behaviour while trying to use pyoidc with QGIS 2.18.x windows standalone version.
Due to pip/pipy no longer working with QGIS 2.18 (see this post), we installed the ...
4
votes
0answers
2k views
Using polygons to create mask on 2d grid with Python?
I have some polygons (Canadian provinces), read in with GeoPandas, and want to use these to create a mask to apply to gridded data on a 2-d latitude-longitude grid (read from a netcdf file using iris)....
4
votes
0answers
692 views
How to perform spatial join and obtain attribute in python/GDAL?
I am working on a script that will take an unprojected raster, and using a UTM grid (shapefile), will obtain the correct SRS (I have a shapefile where each zone is attributed with its numerical SRS) ...
4
votes
0answers
703 views
Install OSGeo module in virtualenv
How can you install the osgeo module in a virtualenv? I downloaded QGIS using KyngChaos (www.kyngchaos.com/software/qgis) following https://arset.gsfc.nasa.gov/sites/default/files/land/webinars/...
4
votes
1answer
182 views
QField — using Python init functions
We are using the field mapping application QField with QGIS 2.18 for on-site data collection.
I've looked through the documentation and am still unsure, so am bring this question here: Is it possible ...
4
votes
0answers
184 views
PyQGIS composed Atlas generation
I have some layers :
layer 1
layer 2
layer 3
and I have create styles for any labels layer using base rule styles and labels and I have create a template .qpt and I use atlas correct.
In my ...
4
votes
0answers
509 views
Import Pandas or any Python module into QGIS internal Python
(Also asked in stack overflow -
https://stackoverflow.com/questions/43244062/import-pandas-or-any-python-module-into-qgis-internal-python )
I am developing a plugin for the current LTR version of ...
4
votes
0answers
566 views
Right-hand-rule in QGIS
It seems that there isn't a plugin to perform the right-hand-rule on a layer or selected features. Can this be done by using some Python code? Is there a function that works in the same way as ...
4
votes
0answers
751 views
Shapely polygons crossing the antimeridian
Sample data
Consider the following WKT Polygon, crossing the international dateline (antimeridian):
POLYGON((176 49,-65 49,-65 11,176 11,176 49))
And the following points:
POINT(-140 32) # ...
4
votes
0answers
2k views
What is the fastest version of gdal2tiles?
I have multi-CPU linux server, so I wonder what is the fastest parallel version of gdal2tiles.py ?
My Ubuntu version:
lsb_release -a
Description: Ubuntu 12.04.5 LTS
How I install the package:
...
4
votes
0answers
291 views
netCDF has wrong spatial extent in metadata
I have a netCDF file with spatial data ranging from x:528500 573500 y:350500 399500 on EPSG: 31287. If I open and explore the file with Panoply and show the data on a map all works like it should.
...
4
votes
0answers
161 views
Gdal Python problem: black strips in image translation
I have a 500 x 500 m resolution world map of clumping index data (He et al., 2012) and I am trying to do two things at the same time: 1) to isolate the variables per plant functional type following ...
4
votes
0answers
511 views
ATDI free map read with software
I am interested in working with the freely available ATDI MAPS. The maps are provided for their proprietary software ICS manager or ICS telecom. I am involved in a project to develop a software in c++ ...
4
votes
0answers
221 views
How to handle large tables in QGIS using python?
I'm currently writing a plugin that calculates values based on a QgsVectorLayer's attributes. To display and print the values I'm using a QgsComposerTextTableV2. I have several problems with my ...
4
votes
0answers
1k views
GDAL RasterIO performance in C++ vs ReadAsArray in python/numpy
I'm currently writing optimisations for a raster viewer program which uses gdal as it's base. It's currently written purely in python, and has some major speed issues which cause problems when we are ...
4
votes
0answers
92 views
Issues updating field values programmatically for particular field data type on 64bit Windows computer using QGIS 2.8.7
I have an issue with a plugin for QGIS 2.8 I'm developing when using it on a Windows 64bit machine (as opposed to 32bit).
I am trying to update values in a particular field in my plugin, and the ...
4
votes
0answers
105 views
Open QGIS project files in exclusive mode / alert if project file already in use
I have QGIS-Project-Files saved to a network drive and was wondering if it is possible to warn users that a project file is already opened by an other user to prevent concurrent editing of the same ...
4
votes
0answers
349 views
PyQGIS: vector layer does not get displayed after rendering
My project goal is to write a standalone app for Unbuntu and QGIS 2.14. It should get a layer of simple points and their name from a Postgres database and show them in a layer. In addition there ...
4
votes
1answer
266 views
How to show only selected features from a a layer in the QgsComposerLegend?
I have developed a custom qgis plugin. I have a button to export the map canvas in the form of image along with the legend. I came up with the following code for the legend:
legend = ...
4
votes
0answers
72 views
“Merging” 2 layers of LineString with splits at intersections
I would like to "merge" 2 networks of lines and these lines need to be split when they intersect. With pictures it should be clearer :
What to do:
if a black line intersects a red line, they should ...
3
votes
0answers
48 views
How to get a layer object from a geometry
I have a polygon as a gdal geometry and I'd like to use it with gdal.RasterizeLayer(). As its name states, this method needs a layer object, not a geometry. So I need to convert/wrap my geometry into ...
3
votes
0answers
425 views
Math domain error in slippy tiles generator
I'm running Alexander Hajnal's Python module (http://alephnull.net/software/gis/tile_writer.shtml) in QGIS (2.14.3, Win10 64) and I'm using the EPSG:3857 as crs.
I got this error:
"Traceback (most ...
3
votes
0answers
279 views
QGIS selecting features and using field calculator to update existing field using python
I am wondering how to select features based on conditions from multiple fields to update an existing field in QGIS.
This is the code I have so far. The expression I want to use to select features is ...
3
votes
0answers
163 views
Python QGIS crashes within categorized renderer setup
I'm hassling around with QGIS renderer definitions in python with QGIS 2.8 at debian wheezy. At least I want simply build step by step a categorized renderer to fill a polygon. The script crashes, ...
3
votes
0answers
137 views
TypeError: QgsEncodingFileDialog
I am using the latest version of QGIS (Lyon) on MAC and have set the default Python version 2.7. Moreover, I have installed all the required python modules and GDAL.
It was working before, but now, ...
