pyvista_zstd.Reader#

Class to control pyvista-zstd file decompression.

Use this class in lieu of pyvista_zstd.read() to fine-tune reading in compressed files. With this you can:

Inspect the dataset before reading it.
Control which arrays to read in.
For files containing a pyvista.MultiBlock, select which blocks to read in.

A container already resident is read by passing buffer instead of filename – an archive member, a response body, or a build with no filesystem to open a path on. Those bytes are borrowed rather than copied and are held for the reader’s life, so they must not be modified meanwhile. Writing into them is not detected: the arrays read afterwards hold undefined contents, and no error is raised to say so. Resizing them is detected – the borrow pins the buffer, so a resize raises BufferError rather than corrupting anything.

A reader holds the file mapped, or the caller’s buffer alive, until close() – which with calls on the way out:

with pyvista_zstd.Reader(buffer=raw) as reader:
    ds = reader.read()

Parameters:

filenamepathlib.Path | str, optional: Path to the file. Must end in .pv.
bufferbytes | bytearray | memoryview | numpy.ndarray, optional: A whole container, contiguous. Exactly one of filename and buffer is given; a buffer has no suffix to check, so its bytes decide whether it is a container.
backendstr, optional: Deprecated and ignored; passing it raises a DeprecationWarning.

Attributes:

available_cell_arrays: Return a set of all cell array names available in the dataset.
available_field_arrays: Return a set of all field array names available in the dataset.
available_point_arrays: Return a set of all point array names available in the dataset.
decompressed_sizes: Return decompressed frame sizes.
nbytes: Return the size of the decompressed dataset.
selected_cell_arrays: Return the set of currently selected cell arrays to read.
selected_field_arrays: Return the set of currently selected field arrays to read.
selected_point_arrays: Return the set of currently selected point arrays to read.

Methods

`close`()	Release the container.
`read`([n_threads])	Read in the dataset from the pyvista-zstd file.
`show_frame_compression`()	Return a table showing compression statistics for each frame in the dataset.

Examples

First write out an example dataset.

>>> import pyvista as pv
>>> import pyvista_zstd
>>> ds = pv.Sphere()
>>> pyvista_zstd.write(ds, "sphere.pv")

Create a reader.

>>> reader = pyvista_zstd.Reader("sphere.pv")
>>> reader
pyvista_zstd.Reader (0x7f1ed1496c00)
  File:               sphere.pv
  File Version:       0
  Compression:        zstandard
  Compression Level:  3
  Dataset Type:       PolyData
  N Points:           842 (<class 'numpy.float32'>)
  N Cells:            1680
  Point arrays:
      Normals                  float32    (842, 3)

Disable reading in point arrays and read the dataset.

>>> reader.selected_point_arrays = set()
>>> ds_in = reader.read()
>>> ds_in
PolyData (0x7f1ece066ce0)
  N Cells:    1680
  N Points:   842
  N Strips:   0
  X Bounds:   -4.993e-01, 4.993e-01
  Y Bounds:   -4.965e-01, 4.965e-01
  Z Bounds:   -5.000e-01, 5.000e-01
  N Arrays:   0

Read the same container out of memory instead of off disk.

>>> from pathlib import Path
>>> raw = Path("sphere.pv").read_bytes()
>>> ds_in = pyvista_zstd.Reader(buffer=raw).read()

Methods

`Reader.__init__`([filename, buffer, backend])	Initialize the decompressor.
`Reader.close`()	Release the container.
`Reader.read`([n_threads])	Read in the dataset from the pyvista-zstd file.
`Reader.show_frame_compression`()	Return a table showing compression statistics for each frame in the dataset.

Attributes

`Reader.available_cell_arrays`	Return a set of all cell array names available in the dataset.
`Reader.available_field_arrays`	Return a set of all field array names available in the dataset.
`Reader.available_point_arrays`	Return a set of all point array names available in the dataset.
`Reader.decompressed_sizes`	Return decompressed frame sizes.
`Reader.nbytes`	Return the size of the decompressed dataset.
`Reader.selected_cell_arrays`	Return the set of currently selected cell arrays to read.
`Reader.selected_field_arrays`	Return the set of currently selected field arrays to read.
`Reader.selected_point_arrays`	Return the set of currently selected point arrays to read.

pyvista_zstd.Reader

Contents

pyvista_zstd.Reader#