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#!/usr/bin/env python2.7
# Copyright 2017, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
# * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
""" The math behind the diff functionality """
from scipy import stats
import math
_THRESHOLD = 1e-10
def scale(a, mul):
return [x * mul for x in a]
def cmp(a, b):
return stats.ttest_ind(a, b)
def speedup(new, old):
if (len(set(new))) == 1 and new == old: return 0
s0, p0 = cmp(new, old)
if math.isnan(p0): return 0
if s0 == 0: return 0
if p0 > _THRESHOLD: return 0
if s0 < 0:
pct = 1
while pct < 101:
sp, pp = cmp(new, scale(old, 1 - pct / 100.0))
if sp > 0: break
if pp > _THRESHOLD: break
pct += 1
return -(pct - 1)
else:
pct = 1
while pct < 100000:
sp, pp = cmp(new, scale(old, 1 + pct / 100.0))
if sp < 0: break
if pp > _THRESHOLD: break
pct += 1
return pct - 1
if __name__ == "__main__":
new = [1.0, 1.0, 1.0, 1.0]
old = [2.0, 2.0, 2.0, 2.0]
print speedup(new, old)
print speedup(old, new)
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