Compressor: Field compression module

Preamble

Compressor enables fields compression for arrays/pyTrees.

This module is part of Cassiopee, a free open-source pre- and post-processor for CFD simulations.

To use the module with the Compressor array interface:

import Compressor

To use the module with the CGNS/Python interface:

import Compressor.PyTree as Compressor

List of functions

– Index field compression

Compressor.deltaIndex(index, ref) Return the delta between index and ref.

– Object serializer/compression

Compressor.pack(a[, method]) Serialize or compress a.
Compressor.unpack(a[, method]) Deserialize or decompress a.

Contents

Index field compression

Compressor.deltaIndex(a, ref)

Compress a list of indices using delta algorithm. The return Delta contains the number of added indices in a when compared to ref, the list of added indices, the number of suppressed indices, the list of suppressed indices.

Parameters:
  • a (numpy of ints) – input indices
  • ref (numpy) – compared indices
Returns:

list of added indices, the number of supressed indices, list of suppress indices
Return type:

(numpy, int, numpy)

 
# - deltaIndex -
import numpy
import Compressor

# Liste des indexes de reference
indRef = numpy.array([1,2,3,4,5], dtype='int32')

# Liste des indexes a comparer a la reference
index = numpy.array([1,2,3,4], dtype='int32')

delta = Compressor.deltaIndex(index, indRef)
print(delta)

Object serialize/compression

Compressor.pack(a)

Serialize/compress a python object a. For now, this is only a general interface to pickle module.

Parameters:a (python object) – any python object
Returns:serialized stream 
# - pack -
import Compressor
import Generator.PyTree as G
a = G.cart((0,0,0), (1,1,1), (1000,100,100))
b = Compressor.pack(a)
Compressor.unpack(a)

Deserialize/decompress a serialized stream b. For now, this is only a general interface to pickle module.

Parameters:a (serialized stream) – a serialized stream as produced by pack
Returns:python object 
# - unpack -
import Compressor
import Generator.PyTree as G
a = G.cart((0,0,0), (1,1,1), (1000,100,100))
b = Compressor.pack(a)
c = Compressor.unpack(b)