Questions tagged [python]
Python is an open source interpreted programming language used in many GIS programs.
1,744
questions with no upvoted or accepted answers
13
votes
0answers
533 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 ...
10
votes
0answers
382 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 ...
9
votes
0answers
305 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 ...
8
votes
0answers
341 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 ...
7
votes
0answers
259 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
1k 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 ...
6
votes
0answers
47 views
OGR failing to unpack polygons and respective holes from shapefile
I'm trying to unpack shapefiles in Python (v3.7.4) using the GDAL-OGR library (v2.3.3). Each shapefile has only one feature containing multiple polygons with holes. They cannot be produced differently....
6
votes
0answers
208 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 ...
6
votes
0answers
294 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 ...
6
votes
0answers
2k views
Get rid of jumping GPS data with pykalman
I have gps data that I get from a smartphone application. Whenever the smartphone is stationary, the gps points are jumping. I understand that the signal is inaccurate due to the reception in a city ...
6
votes
0answers
1k 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 ...
6
votes
0answers
243 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
74 views
QGIS 3.6 and QGIS 3.10 report different geometry types for the same shapefile
I used QGIS 3.6.3 to create a polyline shapefile, and the program reported the polyline as LineStringZM. When I opened the same shape file in QGIS 3.10.3-2, the polyline was reported as ...
5
votes
1answer
47 views
Resolve Intersecting areas in shapefile
I combined two shapefiles and noticed that the polygons didn't overlay perfectly.
How can I resolve these intersections to snap to their closest neighbours?
This is a closer look at the intersections:...
5
votes
0answers
129 views
Nearest neighbour joins for two geodataframes using KDtree from scipy/sklearn
I have a number of large geodataframes and want to automate the implementation of a Nearest Neighbour function using a KDtree for more efficient processing. The process I want to achieve here is to ...
5
votes
0answers
47 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 ...
5
votes
0answers
320 views
Labelling a rubber band (QgsRubberBand)
It is possible to label QgsRubberBand or QgsVertexMarker with a text annotation (QgsTextAnnotationItem).
See this MWE:
...
r_polyline = QgsRubberBand(iface.mapCanvas(), False)
r_polyline....
5
votes
0answers
120 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 ...
5
votes
1answer
508 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
1answer
590 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
90 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 ...
5
votes
0answers
562 views
Setting up PyCharm CE 4 to work with PyQGIS library in Mac OS
I am trying to set up pycharm to work with pyQgis library but with not success till now. I am using PyCharm CE v4 and QGIS version 2.8 I have tried to implemnte the instructions of several posts like ...
5
votes
2answers
5k views
WindowsError: [Error 32] The process cannot access the file because it is being used by another process
I am reading images (through Python) and do something. These images are placed in a temporary file, through:
tf = tempfile.mkdtemp(filename)
I use gdal to read the images (short part of code):
...
...
5
votes
0answers
1k views
Geoprocessing Service on ArcGIS Server to Export File
ArcGIS Server /
Geoprocessing Question
I have a geoprocessing service that will perform a selection on a layer based on a provided expression. I would like to output the result as a csv file (or ...
5
votes
0answers
891 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
358 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
0answers
34 views
QGIS processing tools - saving/exporting graph
I just tried QGIS processing tools for the first time.
When using shortest path search for the first time, the algorithm is building a path graph (of course). However, the graph is never re-used. ...
4
votes
0answers
48 views
Open multiple QGIS projects via PyQGIS simultaneously in different threads
I'm writing a standalone PyQGIS application. When the method qgis() is called in a new thread, it's supposed to open a QGIS project (with one layer in it) and close it again:
from concurrent.futures....
4
votes
0answers
30 views
Python osgeo/OGR not returning all features in PBF
I have a PBF file that is a limited export of the Nepal area. I'm trying to pull out all the adminstrative boundaries.
If I use osmconvert to turn my PBF file into a OSM file, sure enough I see the ...
4
votes
0answers
93 views
QGIS 3: Set custom project variables with input dialog
I am using QGIS 3.10.0 and Windows 10. I have a project where I want the user to define custom project variables. I want to make this user friendly, I don't want the user to need to open the project ...
4
votes
0answers
493 views
Georeference an unreferenced image using rasterio in Python
I have unregistered/unreferenced 6 band TIFF images that I have been trying to export as georeferenced GeoTIFFs. The GPS coordinates of the corners of each image is known and each image is 1024 height ...
4
votes
1answer
70 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
1answer
910 views
Creating shapefile file with Fiona and GeoPandas?
I am trying to create a shapefile and a geojson using geopandas and fiona.
import fiona
import fiona.crs
...
geometry = [Point(xy) for xy in zip(df['longitude'],df['latitude'])]
crs = {'init': '...
4
votes
0answers
191 views
QGIS plugin external libraries in plugin’s directory
I’m developing my first QGIS plugin and I have to use two external libraries not included in the default OSGeoW64 installation: Couchdb and Pandas.
I would like to include those libraries in my ...
4
votes
0answers
124 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
253 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
3k 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
939 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
734 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
0answers
657 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
682 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
1k 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
3k 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
252 views
How to add a Google map layer in a pyqgis script
I'm creating a python plugin for different users that has the layers that each person need to use and work with in QGIS.
I have no trouble adding rasters from Geoserver using the following code:
...
4
votes
0answers
385 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
172 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
595 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
839 views
Click to copy coordinates From QGIS
I have a created some point data using CRS ESPG:4326 and added Google base map from OpenLayers plugin. While adding the Google Maps imagery I have changed CRS to ESPG:3857 in project properties.
...
4
votes
0answers
243 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 ...
