What is the best approach to create a create a very large shapefile (close to the max of 2GB) using python? Best approach means: robust and fast. Above all fast.
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Why the downvote?– LarsVegasAug 14, 2013 at 13:41
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10May be because of lack of information in your question? IMHO best practice in your case is NOT TO USE shp-files at all. Use spatial databases for such amount of data.– SS_RebeliousAug 14, 2013 at 13:48
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1Out of what will you create this shapefile? Surely there are some inputs or specifications--otherwise, the fastest way is to use an operating system call to copy an existing 2 GB shapefile :-).– whuberAug 14, 2013 at 15:23
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1Haha! Good one. Well, this question was intended to be open. There is one specific use case right now (~700.000 point geomtries with two attribute columns (strings)) but I was interested in general thoughts about fast ways to create a shapefile from scratch.– LarsVegasAug 14, 2013 at 15:56
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1@SS_Rebelious, in many cases I agree, since they have several limitations. However, in simpler circumstances shapefiles are still useful, e.g supported by numerous systems, quick & easy to handle etc.– OyvindAug 14, 2013 at 17:31
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3 Answers
I want to take the chance of promoting OGR's virtual file system that writes geometries to a in-memory dataset.
Using it is simple as @Luke demonstrated in this post
drv = ogr.GetDriverByName( 'ESRI Shapefile' )
ds = drv.CreateDataSource(r'/vsimem/virtual.shp')
This works just great. Creating a point shape file with ~300.000 geometries and two attribute fields takes less than two seconds. Impressive.
answered Aug 23, 2013 at 11:34
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If your dealing with a really large shape file won't this get slow once it eats all your memory and swaps? May 26, 2015 at 15:05
A slow method is updating the shapefile, on disk, for each record. I would look for a Python library that allows you to create an in-memory layer, then write the shapefile to disk in a single function or transactions. Fione/shapely may offer something. Also, ogr2ogr will create a shapefile from csv, or another shapefile, etc. Ogr2ogr is written in C or C++ so it should be fast, but is not a pure Python solution. You'll want to define the shapefile attributes as tight as possible to keep the shapefile as small as possible.
If Python is desired for this task, then the GDAL/OGR Python bindings is probably the best free option.
See HERE for a python example showing how to create/write to a shapefile.
