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# encoding: utf-8
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"""Classes used in scattering and gathering sequences.
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Scattering consists of partitioning a sequence and sending the various
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pieces to individual nodes in a cluster.
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"""
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__docformat__ = "restructuredtext en"
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#-------------------------------------------------------------------------------
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# Copyright (C) 2008 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-------------------------------------------------------------------------------
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#-------------------------------------------------------------------------------
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# Imports
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#-------------------------------------------------------------------------------
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import types
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from IPython.genutils import flatten as genutil_flatten
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#-------------------------------------------------------------------------------
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# Figure out which array packages are present and their array types
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#-------------------------------------------------------------------------------
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arrayModules = []
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try:
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import Numeric
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except ImportError:
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pass
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else:
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arrayModules.append({'module':Numeric, 'type':Numeric.arraytype})
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try:
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import numpy
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except ImportError:
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pass
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else:
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arrayModules.append({'module':numpy, 'type':numpy.ndarray})
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try:
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import numarray
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except ImportError:
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pass
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else:
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arrayModules.append({'module':numarray,
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'type':numarray.numarraycore.NumArray})
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class Map:
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"""A class for partitioning a sequence using a map."""
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def getPartition(self, seq, p, q):
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"""Returns the pth partition of q partitions of seq."""
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# Test for error conditions here
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if p<0 or p>=q:
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print "No partition exists."
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return
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remainder = len(seq)%q
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basesize = len(seq)/q
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hi = []
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lo = []
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for n in range(q):
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if n < remainder:
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lo.append(n * (basesize + 1))
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hi.append(lo[-1] + basesize + 1)
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else:
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lo.append(n*basesize + remainder)
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hi.append(lo[-1] + basesize)
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result = seq[lo[p]:hi[p]]
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return result
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def joinPartitions(self, listOfPartitions):
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return self.concatenate(listOfPartitions)
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def concatenate(self, listOfPartitions):
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testObject = listOfPartitions[0]
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# First see if we have a known array type
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for m in arrayModules:
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#print m
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if isinstance(testObject, m['type']):
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return m['module'].concatenate(listOfPartitions)
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# Next try for Python sequence types
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if isinstance(testObject, (types.ListType, types.TupleType)):
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return genutil_flatten(listOfPartitions)
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# If we have scalars, just return listOfPartitions
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return listOfPartitions
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class RoundRobinMap(Map):
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"""Partitions a sequence in a roun robin fashion.
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This currently does not work!
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"""
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def getPartition(self, seq, p, q):
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return seq[p:len(seq):q]
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#result = []
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#for i in range(p,len(seq),q):
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# result.append(seq[i])
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#return result
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def joinPartitions(self, listOfPartitions):
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#lengths = [len(x) for x in listOfPartitions]
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#maxPartitionLength = len(listOfPartitions[0])
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#numberOfPartitions = len(listOfPartitions)
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#concat = self.concatenate(listOfPartitions)
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#totalLength = len(concat)
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#result = []
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#for i in range(maxPartitionLength):
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# result.append(concat[i:totalLength:maxPartitionLength])
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return self.concatenate(listOfPartitions)
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dists = {'b':Map}
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