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#!/usr/bin/env python
from __future__ import print_function
import sys
if sys.hexversion < 0x03000000:
from future_builtins import zip
################################################################################
#
# adjacent_pairs_iterate.py
#
#
# Copyright (c) 2007 Leo Goodstadt
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#################################################################################
def adjacent_pairs_iterate (array, reverse = False):
"""
returns pairs of iterators to successive positions
"""
if len(array) < 2:
return
# get iterators to successive positions
if reverse:
curr_iter = reversed(array)
next_iter = reversed(array)
else:
curr_iter = iter(array)
next_iter = iter(array)
next(next_iter)
for i, j in zip(curr_iter, next_iter):
yield i, j
def unit_test():
numbers = list(range(10))
print("Forward")
for i, j in adjacent_pairs_iterate(numbers):
print(i, j)
print("Reversed")
for i, j in adjacent_pairs_iterate(numbers, reverse=True):
print(i, j)
print(numbers)
if __name__ == '__main__':
unit_test()
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