Python FastRBTree.floor_item方法代码示例

# 需要导入模块: from bintrees import FastRBTree [as 别名]
# 或者: from bintrees.FastRBTree import floor_item [as 别名]
class ExclusiveRangeDict(object):
  """A class like dict whose key is a range [begin, end) of integers.

  It has an attribute for each range of integers, for example:
  [10, 20) => Attribute(0),
  [20, 40) => Attribute(1),
  [40, 50) => Attribute(2),
  ...

  An instance of this class is accessed only via iter_range(begin, end).
  The instance is accessed as follows:

  1) If the given range [begin, end) is not covered by the instance,
  the range is newly created and iterated.

  2) If the given range [begin, end) exactly covers ranges in the instance,
  the ranges are iterated.
  (See test_set() in tests/range_dict_tests.py.)

  3) If the given range [begin, end) starts at and/or ends at a mid-point of
  an existing range, the existing range is split by the given range, and
  ranges in the given range are iterated.  For example, consider a case that
  [25, 45) is given to an instance of [20, 30), [30, 40), [40, 50).  In this
  case, [20, 30) is split into [20, 25) and [25, 30), and [40, 50) into
  [40, 45) and [45, 50).  Then, [25, 30), [30, 40), [40, 45) are iterated.
  (See test_split() in tests/range_dict_tests.py.)

  4) If the given range [begin, end) includes non-existing ranges in an
  instance, the gaps are filled with new ranges, and all ranges are iterated.
  For example, consider a case that [25, 50) is given to an instance of
  [30, 35) and [40, 45).  In this case, [25, 30), [35, 40) and [45, 50) are
  created in the instance, and then [25, 30), [30, 35), [35, 40), [40, 45)
  and [45, 50) are iterated.
  (See test_fill() in tests/range_dict_tests.py.)
  """
  class RangeAttribute(object):
    def __init__(self):
      pass

    def __str__(self):
      return '<RangeAttribute>'

    def __repr__(self):
      return '<RangeAttribute>'

    def copy(self):  # pylint: disable=R0201
      return ExclusiveRangeDict.RangeAttribute()

  def __init__(self, attr=RangeAttribute):
    self._tree = FastRBTree()
    self._attr = attr

  def iter_range(self, begin=None, end=None):
    if not begin:
      begin = self._tree.min_key()
    if not end:
      end = self._tree.max_item()[1][0]

    # Assume that self._tree has at least one element.
    if self._tree.is_empty():
      self._tree[begin] = (end, self._attr())

    # Create a beginning range (border)
    try:
      bound_begin, bound_value = self._tree.floor_item(begin)
      bound_end = bound_value[0]
      if begin >= bound_end:
        # Create a blank range.
        try:
          new_end, _ = self._tree.succ_item(bound_begin)
        except KeyError:
          new_end = end
        self._tree[begin] = (min(end, new_end), self._attr())
      elif bound_begin < begin and begin < bound_end:
        # Split the existing range.
        new_end = bound_value[0]
        new_value = bound_value[1]
        self._tree[bound_begin] = (begin, new_value.copy())
        self._tree[begin] = (new_end, new_value.copy())
      else:  # bound_begin == begin
        # Do nothing (just saying it clearly since this part is confusing)
        pass
    except KeyError:  # begin is less than the smallest element.
      # Create a blank range.
      # Note that we can assume self._tree has at least one element.
      self._tree[begin] = (min(end, self._tree.min_key()), self._attr())

    # Create an ending range (border)
    try:
      bound_begin, bound_value = self._tree.floor_item(end)
      bound_end = bound_value[0]
      if end > bound_end:
        # Create a blank range.
        new_begin = bound_end
        self._tree[new_begin] = (end, self._attr())
      elif bound_begin < end and end < bound_end:
        # Split the existing range.
        new_end = bound_value[0]
        new_value = bound_value[1]
        self._tree[bound_begin] = (end, new_value.copy())
#.........这里部分代码省略.........

# 需要导入模块: from bintrees import FastRBTree [as 别名]
# 或者: from bintrees.FastRBTree import floor_item [as 别名]
prev[ 0 ] = 0
cur = FastRBTree()
cur[ 0 ] = 0
i = 0
for elem in newInput:
   v = elem[ 2 ]
   w = elem[ 1 ]
   #for line in fin:
   #info = line.split()
   #v = int( info[ 0 ] )
   #w = int( info[ 1 ] )
   #print newItems - i, (v,w), len( prev )#, len( testSet )
   i += 1
   for stepWeight in prev:
      step = [ stepWeight, prev[ stepWeight ] ]
      curv = cur.floor_item( step[ 0 ] )[ 1 ]
      maxv = max( step[ 1 ], curv )
      # compare prev and cur on same weight
      if maxv == step[ 1 ]:
         cur[ step[ 0 ] ] = maxv

      nextw = step[ 0 ] + w
      # using step weight as base, compare value of 
      # prev val( step weight ) + item val --> with current item
      # and prev val( step weight + item weight ) --> without current item
      if nextw < size and prev.floor_item( nextw )[ 1 ] < step[ 1 ] + v:
         cur[ nextw ] = step[ 1 ] + v
   prev = cur
   cur = FastRBTree()
   cur[ 0 ] = 0