FAQ

How do I initialize a list property from a two-dimensional array?

>>> from plyfile import PlyElement
>>> import numpy
>>>
>>> # Here's a two-dimensional array containing vertex indices.
>>> face_data = numpy.array([[0, 1, 2], [3, 4, 5]], dtype='i4')
>>>
>>> # PlyElement.describe requires a one-dimensional structured array.
>>> ply_faces = numpy.empty(len(face_data),
...                         dtype=[('vertex_indices', 'i4', (3,))])
>>> ply_faces['vertex_indices'] = face_data
>>> face = PlyElement.describe(ply_faces, 'face')
>>>

Can I save a PLY file directly to sys.stdout?

Yes, for an ASCII-format PLY file. For binary-format files, it won’t work directly, since sys.stdout is a text-mode stream and binary-format files can only be output to binary streams. (ASCII-format files can be output to text or binary streams.)

There are a few ways around this.

  • Write to a named file instead. On Linux and some other Unix-likes, you can access stdout via the named file /dev/stdout:

    >>> plydata.write('/dev/stdout')  # doctest: +SKIP

  • Use sys.stdout.buffer:

    >>> plydata.write(sys.stdout.buffer)  # doctest: +SKIP

Can I read a PLY file from sys.stdin?

The answer is exactly analogous to the situation with writing to sys.stdout: it works for ASCII-format PLY files but not binary-format files. The two workarounds given above also apply: use a named file like /dev/stdin, or use sys.stdin.buffer.