class Interval(object):
"""
Represents an interval.
Defined as half-open interval [start,end), which includes the start position but not the end.
Start and end do not have to be numeric types.
"""
def __init__(self, start, end):
"Construct, start must be <= end."
if start > end:
raise ValueError('Start (%s) must not be greater than end (%s)' % (start, end))
self._start = start
self._end = end
start = property(fget=lambda self: self._start, doc="The interval's start")
end = property(fget=lambda self: self._end, doc="The interval's end")
def __str__(self):
"As string."
return '[%s,%s)' % (self.start, self.end)
def __repr__(self):
"String representation."
return '[%s,%s)' % (self.start, self.end)
def __cmp__(self, other):
"Compare."
if None == other:
return 1
start_cmp = cmp(self.start, other.start)
if 0 != start_cmp:
return start_cmp
else:
return cmp(self.end, other.end)
def __hash__(self):
"Hash."
return hash(self.start) ^ hash(self.end)
def intersection(self, other):
"Intersection. @return: An empty intersection if there is none."
if self > other:
other, self = self, other
if self.end <= other.start:
return Interval(self.start, self.start)
return Interval(other.start, self.end)
def hull(self, other):
"@return: Interval containing both self and other."
if self > other:
other, self = self, other
return Interval(self.start, other.end)
def overlap(self, other):
"@return: True iff self intersects other."
if self > other:
other, self = self, other
return self.end > other.start
def __contains__(self, item):
"@return: True iff item in self."
return self.start <= item and item < self.end
def zero_in(self):
"@return: True iff 0 in self."
return self.start <= 0 and 0 < self.end
def subset(self, other):
"@return: True iff self is subset of other."
return self.start >= other.start and self.end <= other.end
def proper_subset(self, other):
"@return: True iff self is proper subset of other."
return self.start > other.start and self.end < other.end
def empty(self):
"@return: True iff self is empty."
return self.start == self.end
def singleton(self):
"@return: True iff self.end - self.start == 1."
return self.end - self.start == 1
def separation(self, other):
"@return: The distance between self and other."
if self > other:
other, self = self, other
if self.end > other.start:
return 0
else:
return other.start - self.end
