text: # ==================================================================================================
  # Copyright 2015 Twitter, Inc.
  # --------------------------------------------------------------------------------------------------
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this work except in compliance with the License.
  # You may obtain a copy of the License in the LICENSE file, or at:
  #
  #  http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==================================================================================================
  
  """
  get percentile for values (https://en.wikipedia.org/wiki/Percentile)
  (roughly Linear Interpolation Between Closest Ranks)
  
  From:
    https://github.com/twitter/zktraffic/blob/master/zktraffic/stats/util.py
  """
  
  import math
  
  
  def percentile(values, percent, key=lambda k: k):
  
    assert isinstance(values, (list, tuple))
  
    idx = (len(values) - 1) * percent
    floor = math.floor(idx)
    ceil = math.ceil(idx)
    if floor == ceil:
      return key(values[int(idx)])
  
    a = key(values[int(floor)]) * (ceil - idx)
    b = key(values[int(ceil)]) * (idx - floor)
  
    return a + b
  
  