I constantly use these Python patterns for searching sorted iterables of continuous points

point_bisect.py

#!/usr/bin/env python
# point_bisect.py
# Kyle Gorman
# 
# I continually use these two patterns in Python for iterables that contain
# continuous values, sorted. Here they are in their full glory.

from bisect import bisect_left


def nearest(query, sequence):
    """
    Return the value in sequence, an sorted object indexed by integer/slice 
    keys, which is nearest to the query

    >>> sequence = [.2, .3, .8]
    >>> print nearest(.1, sequence)
    0.2
    >>> print nearest(.2, sequence)
    0.2
    >>> print nearest(.3, sequence)
    0.3
    >>> print nearest(.4, sequence)
    0.3
    >>> print nearest(.7, sequence)
    0.8
    >>> print nearest(1., sequence)
    0.8
    """
    i = bisect_left(sequence, query)
    if i == 0: return sequence[0]
    elif i == len(sequence): return sequence[-1]
    elif sequence[i] - query > query - sequence[i - 1]: return sequence[i - 1]
    else: return sequence[i]


def within(query, sequence, offset):
    """
    Return True if there is some numeric element within the sequence which is
    within offset of query, or return False otherwise

    >>> sequence = [.2, .3, .8]
    >>> print within(0., sequence, .1)
    False
    >>> print within(.1, sequence, .2)
    True
    >>> print within(.2, sequence, .1)
    True
    >>> print within(.9, sequence, .1)
    True
    >>> print within(1., sequence, .1)
    False
    """
    i = bisect_left(sequence, query)
    if i == 0: return sequence[0] - query <= offset
    elif i == len(sequence): return query - sequence[-1] <= offset
    elif sequence[i] - query <= offset: return True
    elif query - sequence[i - 1] <= offset: return True
    else: return False


if __name__ == '__main__':
    import doctest
    doctest.testmod()