[pdal] execute a pipeline from python

[Howard Butler]

When you .execute() a pipeline in Python, you get back the data in the pipeline.arrays variable. In a stream scenario, that behavior would be disrupted, or we would need to have it return an iterator or something.

If you want to just execute a pipeline in stream mode without caring for the numpy arrays of the data, is the a reason to not simply use subprocess and invoke the shell?

Howard



> On Jan 31, 2018, at 1:54 PM, Dan Lipsa <dan.lipsa at kitware.com> wrote:
> 
> Hi Howard,
> Thanks for your answer.
> 
> I was thinking more along the lines of what the command line tool does: just set on option "stream" to the pipeline.
> Is this choosing a default chunk (buffer) size?
> 
> For instance the following pipeline takes several point cloud "bricks"
> and generates the dsm for the whole surface covered.
> 
> 
> {
>   "pipeline": [
>     "a.bpf",
>     "b.bpf",
>     {
>       "resolution": 0.25,
>       "filename":"test.tif",
>       "output_type": "max",
>       "window_size": "20",
>       "bounds": "([740698.8745, 741144.3546], [4404897.242, 4405465.48])"
>     }
>   ]
> }
> 
> 
> 
> 
> On Wed, Jan 31, 2018 at 2:43 PM, Howard Butler <howard at hobu.co <mailto:howard at hobu.co>> wrote:
> 
> 
> On 1/31/18 1:37 PM, Dan Lipsa wrote:
> > Hi all,
> > I can enable streaming in a pipeline using
> >
> > ./pdal pipeline --stream dsm.json
> >
> > Can I do the same thing in python?
> > What is the option that I need to set?
> >
> > pipeline = pdal.Pipeline(json)
> > pipeline.validate()  # check if our JSON and options were good
> > count = pipeline.execute()
> >
> 
> Dan,
> 
> No, that bit of Python API isn't done yet. There's a bit of a question
> of what we should do there too? Presumably the API would have the user
> set a chunk size and then return an iterator. The API to follow would be
> the PipelineKernel.cpp implementation, but apply it to the Python/Cython
> extension stuff.
> 
> I'd be happy to merge a patch that did this.
> 
> Howard
> 
> 
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