0
votes
0answers
22 views

Extract pixel value to point file (available) [on hold]

I write a code to extract pixel value to point which had ID (1, 2,3..)(Some point availble). Firstly, I wrote code extract pixel value to text file (.txt). The result is a textfile which had ID ...
0
votes
2answers
59 views

MultiLineString to separate individual lines using Python with GDAL/OGR, Fiona, Shapely

There are lots of MultiLineString features in a polyline shapefile. The problem is to split these lines into separate individual lines. There is a similar question with PostGIS, but I need to code in ...
0
votes
1answer
59 views

Creating records in output shapefile using Python

I have a list (output from a previous loop) containing attributes from an input shapefile. What I am stuck with is inputting those attributes to a new shapefile. I have plotted the point data using ...
0
votes
1answer
75 views

Writing shapefile with projection defined crashes fiona

I've just started trying to use Fiona to write out shapefiles. I found the example code below, which seems to work fine from shapely.geometry import mapping, Polygon import fiona # Here's an example ...
0
votes
1answer
46 views

no viewable feature when creating line with ogr in python

the python code below produces the expected line shapefile viewable in QGIS import os from osgeo import ogr drv=ogr.GetDriverByName('ESRI Shapefile') if os.path.exists('test.shp'): ...
0
votes
1answer
63 views

Get the outer ring inner ring for a given polygon using ogr python binding

I am trying to read the geometry of some shapefiles, now I meet some problem when I try to identify the polygon with holes, since a polygon may(or not) have one hole(or multiple holes). This is the ...
1
vote
1answer
83 views

Union multiple shapefiles with overlapping shapes

I have several shapefiles that overlap and I would like to union their geometries to get rid of those overlaps. I know how to do this with OGR and Python for single geometries. from osgeo import ogr ...
1
vote
1answer
23 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
65 views

GDAL - How to get gemetry type of a MapInfo TAB file?

I am using the OGR MapInfo File driver to read a MapInfo TAB file. However, the function GetGeomType() returns 0 which means 'wkbUnknown` even if the features in the TAB are only multi-polygons. Is ...
0
votes
0answers
55 views

aggregate counts on a grid and determine grid adjacency

So here is the problem I am working on. I have a bunch of lat, long coordinates for event occurrences. I want to create a grid and then count how many points fall into each grid pixel. Once I have ...
0
votes
1answer
82 views

create polygon adjacency matrix using python

I am trying to create an adjacency matrix from a set of polygons. That is, I have a bunch of polygons and I want to identify which polygons have a common edge or "touch" each other. Once I find this ...
1
vote
1answer
63 views

My class using ogr to calculate distance is returning incorrect results away from the equator

In an answer to this question ustroetz kindly provided some sample code for use of ogr to do lat/lon distance and point in polygon calculations. I've created a Python class based on his example to do ...
3
votes
1answer
100 views

Are the functions in OGRPolygon accessible through the python bindings?

I'm currently trying to use the OGR python bindings to process some shapefiles. I want to obtain the number of interior rings in a polygon feature. Unfortunately I'm unable to use the documented ...
0
votes
0answers
14 views

ogr: confusing results from `SetSpatialFilter()`

My layer is derived from a data source like this: l_131 = bounds.ExecuteSQL("select * from 'nam_l' where 'ND_5'= 131 ") feat = l_131.GetNextFeature() feat.GetFeatureCount() >>> 200 It is a ...
0
votes
0answers
23 views

Does a road connect one grid cell to an adjacent grid cell?

So here is the problem I am working on. I have an OpenStreetMap roadmap which I overlaid with a 2-D cartesian grid. So for a given grid square, I want to find out if a road segment continues from the ...
1
vote
1answer
68 views

Equivalent function to shapely's envelope in ogr?

I wrote a very simple python function that gives me the envelope/bounding box/...based on two coordinate pairs (ower left and upper right corner): # ... def get_bounding_box(self, ll_corner, ...
1
vote
1answer
172 views

Import shp to Postgis using Python and ogr

I just export a Postgis Table to shp using this tips but I'm not able to import a shp to Postgis using the same library(ogr). Any idea? Thanks a lot f.
1
vote
1answer
72 views

ogr2ogr/python overwrite PostGIS table

Using ogr2ogr command line I can overwrite or append to an existing PostGIS table like: ogr2ogr -f "PostgreSQL"-overwrite PG:"host=myserver port=54321 user=user dbname=mydbname password=mypassword" ...
3
votes
3answers
518 views

PostGIS: parse geometry wkb with OGR

I'm trying to pull a LineString geometry out of PostGIS and parse it with OGR (python bindinds). from osgeo import ogr import psycopg2 connection = psycopg2.connect("...") cursor = ...
0
votes
0answers
60 views

Getting “Segmentation fault: 11” with ogr in Python

This is the code I'm trying to run: In [1]: from osgeo import ogr In [2]: datasource = ogr.Open('testdata.shp') In [3]: datasource.GetLayerCount() Out[3]: 1 In [4]: layer = ...
0
votes
0answers
77 views

GEOS assertion failed

The following script fails, if I import the 'rasterstats' library. import rasterstats import ogr geom1 = ogr.CreateGeometryFromWkt('POLYGON ((415924.806155724043492 ...
1
vote
1answer
156 views

Why does OGR driver.Open() for File Geodatabase give AttributeError: NoneType object has no attribute Open?

There are a number of existing Questions that hint at a possible Answer to this Question, but none seem to be providing me with the solution to my problem: How to access feature classes in file ...
2
votes
2answers
108 views

Can I use the LEFT (string) operator in ExecuteSQL()?

In QGIS I can use the LEFT operator on a dataset like this: LEFT( "Name2",3) ='031' What is the syntax for using this expression with ogr in python? Isn't this the right syntax? ...
1
vote
1answer
360 views

OGR Layer Intersection

I am using what I would describe as the most primitive method of doing intersection with OGR. The short script below describes how I do it. Is there a best way of doing this? from osgeo import ...
2
votes
1answer
80 views

How can I delete a shapefile using OGR?

In my QGIS Python plugin, I use shapefile layers and I am having a problem rewriting existing shapefiles. Is it possible to delete a shapefile from disk using OGR?
1
vote
2answers
89 views

Difference between OGRGeometry and Geometry in C++ and python

According to the documentation, there is a python version of OGRGeometry's C++ class (http://www.gdal.org/ogr/classOGRGeometry.html) which is http://gdal.org/python/osgeo.ogr.Geometry-class.html ...
6
votes
2answers
342 views

Convert points to lines with Python GDAL

I have a dictionary with points. The points are derived from a raster (see image below). The points are not sorted and are not in order. The dictionary looks for example like this: pointDict = {0: ...
0
votes
2answers
212 views

How to convert gml to geojson using Python and ogr with geometry transformation?

Does anyone have an idea how to convert gml to geojson (with attributes) using Python with ogr bindings? It should be possible to transform geometries to different coordinate system. I can not use ...
1
vote
1answer
157 views

Automatically determine polygon overlap 'islands'

I have a shapefile with many polygons. Some partly overlap with each other, some are not overlapping. I'm considering a polygon to be overlapping given a minimum area of overlap. 'Islands' of partly ...
0
votes
1answer
143 views

Why do Shapefiles and GeoJSON behave differently in GDAL Python?

I have a test.shp. I loop over the file, buffer the features, and write the buffers to a new file. I tested writing the buffers to a Shapefile and to a GeoJSON. If I try to use the new buffer layer ...
2
votes
2answers
88 views

Python-OGR: nested loop only loops once

I have a polygon file buffer_stands.shp with 20 features and I have a line file OSMroads.geojson with 9 features. I expected the script to loop through the buffers and print out for each buffer loop ...
0
votes
1answer
45 views

OGR FeatureCount returns '-1' with OSM data

I am trying to read in an OSM file with OGR. import ogr driverOSM = ogr.GetDriverByName('OSM') roadsDs = driverOSM.Open('data/map.osm', 0) roadsLayer = roadsDs.GetLayer() The feature count returns ...
1
vote
0answers
61 views

What is the best way to handle geometries between Python functions?

What is the best way to handle geometries between different Python functions? For example: I have a function that exports a line from grass.script. The line will be a parameter of another function ...
5
votes
2answers
487 views

Python: how to speed up spatial search (nearest point)?

I'm working on a program that determines the closest location from a given point. The point cloud I'm testing against is very big (~800.000). However, this doesn't really explain why my implementation ...
1
vote
0answers
80 views

How to join attributes by location with command line

I would like to joint the attributes of 2 shapefiles by location but with a command line (linux). This feature is easy in QGIS but it is VERY slow. Is there a way of doing this with ogr or pyqgis ? ...
2
votes
1answer
336 views

Clip and copy files to same directory structure using OGR/GDAL with Python

We need to clip all our data (many TB) by a new boundary and save it while maintaining the same data structure. I want to use OGR/GDAL as the data is in shp/tab/kml/geoTif/ecw etc. I can find the ...
2
votes
2answers
167 views

Change python + ogr2ogr.exe to python + ogr

I have written several complicated python scripts that end up using ogr2ogr to load or translate data. I have been converting these scripts to standalone exe files meaning the team do not require ...
0
votes
2answers
100 views

Python ogr: why is GetFeatureCount() so slow?

I did some profiling for a program I wrote and discovered that ogr's layer.GetFeatureCount() is significantly slower than just using python's BIF len(). Here are my test results def test(): ...
0
votes
2answers
1k views

No ogr module despite having gdal installed?

I am trying to use the mapping component of the wonderful PySAL package, but for some reason I do not have the ogr module. I was under the impression that it came packaged with gdal. Am I missing ...
1
vote
1answer
150 views

OGR: How to best use GetFeature on a selection?

I think the following is very confusing sel_str = "ND_14 = '108'" l.SetAttributeFilter(sel_str) l.GetFeatureCount() >>> 1 In a for-loop this gives me for f in l: g = ...
1
vote
1answer
131 views

OGR: How to save layer from AttributeFilter to a shape filter?

I select a subset of features from my shape file like so: node_lyr = nodes.GetLayer() q_str = "%s = %i" % (field, value) node_lyr.SetAttributeFilter(q_str) What is the best way to make a shape file ...
0
votes
0answers
210 views

GDAL/OGR to extract pixel values

I want to use GDAL/OGR to extract pixel values from a raster file. The extraction should be based on polygons, stored in a shapefile. My thought was to iterate over the features in the shapefile, ...
1
vote
0answers
126 views

How to shift vertices of shapes in shapefile using FOSS python library?

I need to shift each vertice of shape in a shapefile (of any type:point, line, polygon, multiline etc.) with Python. I need to loop in all shapes, get the vertices, get it's coordinates and for each ...
1
vote
1answer
140 views

How to make a virtual layer from ogr geometry?

I know how to do this: nodes = driver.Open(node_nav,0) node_lyr = nodes.GetLayer() node_lyr.SetSpatialFilter(None) But how do can use the layer methods on a geometry I created from scratch? ...
0
votes
1answer
197 views

SetGeometry problems when using python/ogr

So i am trying to use the difference function and i pretty much create the new file i want but the Geometry is empty. No error is produced. any help would great! Thanks. #!/usr/bin/env python import ...
1
vote
2answers
129 views

Erase method using ogr

I'm trying to find the erase geoprocessing method as i am familiar with in ARC, but i can't seem to find it in OGR using Python. I have looked through the module ogr documentation but perhaps i missed ...
2
votes
1answer
89 views

Is there a quicker way of checking if a feature exists with OGR

I'm writing lot's of features to a FileGDB using OGR. The slow point in my script is checking that the feature isn't already in the Feature Class, based on the ID. Currently I'm using a function ...
6
votes
1answer
230 views

Geometry Projection Speed Test

Lately I've been using the OGR projection classes that come with ogr/gdal, but pyproj was recommended to me, so I thought I'd give it a try. To help me decide if I should make the switch, I did a ...
2
votes
2answers
380 views

Python GDAL/OGR: retrieved feature is NoneType

I'm doing some scripts in Python to deal with shapefiles, and I have an issue I don't understand. I'm looping over a shapefile, and I want to retrieve the geometry of each feature, but very often I ...
2
votes
1answer
156 views

How to sort features in a layer using OGR/Python?

How can I sort the features of an ogr layer by the values of a field? I tried naive variations of def sortlayer(ds, layer, field): lname = layer.GetName() lsort = ds.ExecuteSQL(b'select * ...