✨ LaspyReader for reading LAS/LAZ point cloud files

An iterable-style DataPipe for reading LAS/LAZ point cloud files! Uses laspy (with either lazrs or laszip backend) for the I/O. Included a doctest that ensures a LAZ file from OpenTopography can be read. Added a new section in the API docs too.

docs/_config.yml

@@ -54,6 +54,9 @@ sphinx:
       geopandas:
         - 'https://geopandas.org/en/latest/'
         - null
+      laspy:
+        - 'https://laspy.readthedocs.io/en/latest/'
+        - null
       mmdetection:
         - 'https://mmdetection.readthedocs.io/zh_CN/latest/'
         - null

docs/api.md

@@ -27,6 +27,15 @@
     :show-inheritance:
 ```
 
+### Laspy
+
+```{eval-rst}
+.. automodule:: zen3geo.datapipes.laspy
+.. autoclass:: zen3geo.datapipes.LaspyReader
+.. autoclass:: zen3geo.datapipes.laspy.LaspyReaderIterDataPipe
+    :show-inheritance:
+```
+
 ### Pyogrio
 
 ```{eval-rst}

zen3geo/datapipes/__init__.py

@@ -9,6 +9,7 @@
 from zen3geo.datapipes.geopandas import (
     GeoPandasRectangleClipperIterDataPipe as GeoPandasRectangleClipper,
 )
+from zen3geo.datapipes.laspy import LaspyReaderIterDataPipe as LaspyReader
 from zen3geo.datapipes.pyogrio import PyogrioReaderIterDataPipe as PyogrioReader
 from zen3geo.datapipes.pystac import PySTACItemReaderIterDataPipe as PySTACItemReader
 from zen3geo.datapipes.pystac_client import (

zen3geo/datapipes/laspy.py

@@ -0,0 +1,90 @@
+"""
+DataPipes for :doc:`laspy <laspy:index>`.
+"""
+import io
+from typing import Any, Dict, Iterator, Optional
+
+try:
+    import laspy
+except ImportError:
+    laspy = None
+from torchdata.datapipes import functional_datapipe
+from torchdata.datapipes.iter import IterDataPipe
+from torchdata.datapipes.utils import StreamWrapper
+
+
+@functional_datapipe("read_from_laspy")
+class LaspyReaderIterDataPipe(IterDataPipe[StreamWrapper]):
+    """
+    Takes LAS/LAZ files from local disk or an :py:class:`io.BytesIO` stream (as long as
+    they can be read by laspy) and yields :py:class:`laspy.lasdata.LasData` objects
+    (functional name: ``read_from_laspy``).
+
+    Parameters
+    ----------
+    source_datapipe : IterDataPipe[str]
+        A DataPipe that contains filepaths or an :py:class:`io.BytesIO` stream to point
+        cloud files in LAS or LAZ format.
+
+    kwargs : Optional
+        Extra keyword arguments to pass to :py:func:`laspy.read`.
+
+    Yields
+    ------
+    stream_obj : laspy.lasdata.LasData
+        A :py:class:`laspy.lasdata.LasData` object containing the point cloud data.
+
+    Raises
+    ------
+    ModuleNotFoundError
+        If ``laspy`` is not installed. See
+        :doc:`install instructions for laspy <laspy:installation>`, (e.g. via
+        ``pip install laspy[lazrs]``) before using this class.
+
+    Example
+    -------
+    >>> import pytest
+    >>> laspy = pytest.importorskip("laspy")
+    ...
+    >>> from torchdata.datapipes.iter import IterableWrapper
+    >>> from zen3geo.datapipes import LaspyReader
+    ...
+    >>> # Read in LAZ data using DataPipe
+    >>> file_url: str = "https://opentopography.s3.sdsc.edu/pc-bulk/NZ19_Wellington/CL2_BQ31_2019_1000_2138.laz"
+    >>> dp = IterableWrapper(iterable=[file_url])
+    >>> _, dp_stream = dp.read_from_http().unzip(sequence_length=2)
+    >>> dp_laspy = dp_stream.read_from_laspy()
+    ...
+    >>> # Loop or iterate over the DataPipe stream
+    >>> it = iter(dp_laspy)
+    >>> lasdata = next(it)
+    >>> lasdata.header
+    <LasHeader(1.4, <PointFormat(6, 0 bytes of extra dims)>)>
+    >>> lasdata.xyz
+    array([[ 1.74977156e+06,  5.42749877e+06, -7.24000000e-01],
+           [ 1.74977152e+06,  5.42749846e+06, -7.08000000e-01],
+           [ 1.74977148e+06,  5.42749815e+06, -7.00000000e-01],
+           ...,
+           [ 1.74976026e+06,  5.42756798e+06, -4.42000000e-01],
+           [ 1.74976029e+06,  5.42756829e+06, -4.17000000e-01],
+           [ 1.74976032e+06,  5.42756862e+06, -4.04000000e-01]])
+    """
+
+    def __init__(
+        self, source_datapipe: IterDataPipe[str], **kwargs: Optional[Dict[str, Any]]
+    ) -> None:
+        if laspy is None:
+            raise ModuleNotFoundError(
+                "Package `laspy` is required to be installed to use this datapipe. "
+                "Please use `pip install laspy` or "
+                "`conda install -c conda-forge laspy` to install the package"
+            )
+        self.source_datapipe: IterDataPipe[str] = source_datapipe
+        self.kwargs = kwargs
+
+    def __iter__(self) -> Iterator[StreamWrapper]:
+        for lazstream in self.source_datapipe:
+            yield StreamWrapper(laspy.read(source=lazstream, **self.kwargs))
+
+    def __len__(self) -> int:
+        return len(self.source_datapipe)