Funny, I should known what’s in the GDAL FAQ but seems I didn’t
Anyway, we have answer related to your question in there:
How can I merge hundreds of shapefiles?

Thanks for the suggestions- they are fab! (I sense a little batch file coming up…)

Jo

Yes, I think you are right.

Yes – agreed, though I suspect the bottleneck in this case will be reading in the data, building spatial indexes rather than in the pausing and spawning of new processes.

Cheers,

Andrew

…or xargs command:

find . -name ABC | xargs ogr2ogr …

xargs is usually faster than -exec, what may be important while working with huge sets of files.

If you want to do anything with some group of files then find’s exec option is (usually) your friend.

eg to find all the files named ‘MM_TopographicArea_*’ in the current directory (and its subdirectories) and append it to foo.shp you’d do something like:

find . -name MM_TopographicArea_* -exec ogr2ogr -update -append foo.shp {} -nln foo \;

the command in the -exec option is executed for each file matching the -name parameter. The -exec option replaces any instances of {} with the matched filename and is terminated by \;

Hope that helps,

Andrew

You can use ogr2ogr small Shell or Python script that iterates through folders and shapefiles, recognizes similar name prefixes, and calles something like this for every matched shapefiles:

1. Frist, initialize merged shapefile:

ogr2ogr abc_merged.shp subdir1\ abc.shp

2. Append other files with the same name prefix (abc in this example):

ogr2ogr -update -append abc_merged.shp subdir2\abc.shp -nln abc_merged

and so on for subrid3, subdir4, …

Thanks for the heads up- a useful tip IF one is still using ArcGIS! As we are moving towards open source we are looking for alternatives to the things you can do with ESRI products.

Thanks for popping by,

Jo

If have ArcGIS 9.2/9.3
Open ArcMap and ArcCatalog side by side if you can
ArcCatalog>Search on ‘MM_TopographicArea_*.*’
Then select [Shift select]
(This can be done in Windows Explorer as well as ArcCatalog can be slow on many 000’s of files)
drag into ArcMap and they will be order in annotation,point,polyine and polygon. Then use the merge function in the Toolbox to create one file for each data type.

Or use the Geowizards (9.7) [recommended]
http://www.ian-ko.com/
batch merge

Mapperz
http://mapperz.blogspot.com/