Python

PDAL provides Python support in two significant ways. First it embeds Python to allow you to write Python programs that interact with data using filters.python filter. Second, it extends Python by providing an extension that Python programmers can use to leverage PDAL capabilities in their own applications.

Note

PDAL’s Python story always revolves around Numpy support. PDAL’s data is provided to both the filters ands the extension as Numpy arrays.

Versions

PDAL supports both Python 2.7 and Python 3.4+. Continuous Integration tests Python 2.7 on both Linux and Windows. Python 3 is used by a number of developers for adhoc development and testing.

Embed

PDAL allows users to embed Python functions inline with other Pipeline processing operations. The purpose of this capability is to allow users to write small programs that implement interesting actions without requiring a full C++ development activity of building a PDAL stage to implement it. A Python filter is an opportunity to interactively and iteratively prototype a data operation without strong considerations of performance or generality. If something works well enough, maybe one takes on the effort to formalize it, but that isn’t necessary. PDAL’s embed of Python allows you to be as grimy as you need to get the job done.

_images/python-pdal-pipeline.png

Embedding a Python function to take Z values read from a readers.las and then output them to a writers.bpf.

Extend

PDAL provides a Python extension that gives users access to executing Pipeline instantiations and capturing the results as Numpy arrays. This mode of operation is useful if you are looking to have PDAL simply act as your data format and processing handler.

Python extension users are expected to construct their own JSON Pipeline using Python’s json library, or whatever other libraries they wish to manipulate JSON. They then feed it into the extension and get back the results as Numpy arrays:

json = """
{
  "pipeline": [
    "1.2-with-color.las",
    {
        "type": "filters.sort",
        "dimension": "X"
    }
  ]
}"""

import pdal
pipeline = pdal.Pipeline(json)
pipeline.validate() # check if our JSON and options were good
pipeline.loglevel = 8 #really noisy
count = pipeline.execute()
arrays = pipeline.arrays
metadata = pipeline.metadata
log = pipeline.log

Installation

PDAL Python bindings require a working PDAL install (PDAL) and then installation of the Python extension. The extension lives on PyPI at https://pypi.python.org/pypi/PDAL and you should use that version as your canonical Python extension install.

Install from local

In the source code of PDAL there is a python folder, you have to enter there and run

python setup.py build
# this should be run as administrator/super user
python setup.py install

Install from repository

The second method to install the PDAL Python extension is to use pip or easy_install, you have to run the command as administrator.

pip install PDAL

Note

To install pip please read here