Source code for tables.indexes

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#
# License: BSD
# Created: June 02, 2004
# Author:  Francesc Alted - faltet@pytables.com
#
# $Source: /cvsroot/pytables/pytables/tables/indexes.py $
# $Id$
#
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"""Here is defined the IndexArray class."""

from bisect import bisect_left, bisect_right

from .node import NotLoggedMixin
from .carray import CArray
from .earray import EArray
from . import indexesextension


# Declarations for inheriting


class CacheArray(indexesextension.CacheArray, NotLoggedMixin, EArray):
    """Container for keeping index caches of 1st and 2nd level."""

    # Class identifier.
    _c_classid = 'CACHEARRAY'


class LastRowArray(indexesextension.LastRowArray, NotLoggedMixin, CArray):
    """Container for keeping sorted and indices values of last row of an
    index."""

    # Class identifier.
    _c_classid = 'LASTROWARRAY'


[docs]class IndexArray(indexesextension.IndexArray, NotLoggedMixin, EArray): """Represent the index (sorted or reverse index) dataset in HDF5 file. All NumPy typecodes are supported except for complex datatypes. Parameters ---------- parentnode The Index class from which this object will hang off. .. versionchanged:: 3.0 Renamed from *parentNode* to *parentnode*. name : str The name of this node in its parent group. atom An Atom object representing the shape and type of the atomic objects to be saved. Only scalar atoms are supported. title Sets a TITLE attribute on the array entity. filters : Filters An instance of the Filters class that provides information about the desired I/O filters to be applied during the life of this object. byteorder The byteroder of the data on-disk. """ # Class identifier. _c_classid = 'INDEXARRAY' # Properties # ~~~~~~~~~~ @property def chunksize(self): """The chunksize for this object.""" return self.chunkshape[1] @property def slicesize(self): """The slicesize for this object.""" return self.shape[1] # Other methods # ~~~~~~~~~~~~~ def __init__(self, parentnode, name, atom=None, title="", filters=None, byteorder=None): """Create an IndexArray instance.""" self._v_pathname = parentnode._g_join(name) if atom is not None: # The shape and chunkshape needs to be fixed here if name == "sorted": reduction = parentnode.reduction shape = (0, parentnode.slicesize // reduction) chunkshape = (1, parentnode.chunksize // reduction) else: shape = (0, parentnode.slicesize) chunkshape = (1, parentnode.chunksize) else: # The shape and chunkshape will be read from disk later on shape = None chunkshape = None super().__init__( parentnode, name, atom, shape, title, filters, chunkshape=chunkshape, byteorder=byteorder) # This version of searchBin uses both ranges (1st level) and # bounds (2nd level) caches. It uses a cache for boundary rows, # but not for 'sorted' rows (this is only supported for the # 'optimized' types). def _search_bin(self, nrow, item): item1, item2 = item result1 = -1 result2 = -1 hi = self.shape[1] ranges = self._v_parent.rvcache boundscache = self.boundscache # First, look at the beginning of the slice begin = ranges[nrow, 0] # Look for items at the beginning of sorted slices if item1 <= begin: result1 = 0 if item2 < begin: result2 = 0 if result1 >= 0 and result2 >= 0: return (result1, result2) # Then, look for items at the end of the sorted slice end = ranges[nrow, 1] if result1 < 0: if item1 > end: result1 = hi if result2 < 0: if item2 >= end: result2 = hi if result1 >= 0 and result2 >= 0: return (result1, result2) # Finally, do a lookup for item1 and item2 if they were not found # Lookup in the middle of slice for item1 chunksize = self.chunksize # Number of elements/chunksize nchunk = -1 # Try to get the bounds row from the LRU cache nslot = boundscache.getslot(nrow) if nslot >= 0: # Cache hit. Use the row kept there. bounds = boundscache.getitem(nslot) else: # No luck with cached data. Read the row and put it in the cache. bounds = self._v_parent.bounds[nrow] size = bounds.size * bounds.itemsize boundscache.setitem(nrow, bounds, size) if result1 < 0: # Search the appropriate chunk in bounds cache nchunk = bisect_left(bounds, item1) chunk = self._read_sorted_slice(nrow, chunksize * nchunk, chunksize * (nchunk + 1)) result1 = indexesextension._bisect_left(chunk, item1, chunksize) result1 += chunksize * nchunk # Lookup in the middle of slice for item2 if result2 < 0: # Search the appropriate chunk in bounds cache nchunk2 = bisect_right(bounds, item2) if nchunk2 != nchunk: chunk = self._read_sorted_slice(nrow, chunksize * nchunk2, chunksize * (nchunk2 + 1)) result2 = indexesextension._bisect_right(chunk, item2, chunksize) result2 += chunksize * nchunk2 return (result1, result2) def __str__(self): """A compact representation of this class""" return "IndexArray(path=%s)" % self._v_pathname def __repr__(self): """A verbose representation of this class.""" return """{} atom = {!r} shape = {} nrows = {} chunksize = {} slicesize = {} byteorder = {!r}""".format(self, self.atom, self.shape, self.nrows, self.chunksize, self.slicesize, self.byteorder)
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