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###############################################################9
# PyNLPl - Algorithms
# by Maarten van Gompel
# Centre for Language Studies
# Radboud University Nijmegen
# http://www.github.com/proycon/pynlpl
# proycon AT anaproy DOT nl
#
# Licensed under GPLv3
#
###############################################################
from __future__ import print_function
from __future__ import unicode_literals
from __future__ import division
from __future__ import absolute_import
def sum_to_n(n, size, limit=None): #from http://stackoverflow.com/questions/2065553/python-get-all-numbers-that-add-up-to-a-number
"""Produce all lists of `size` positive integers in decreasing order
that add up to `n`."""
if size == 1:
yield [n]
return
if limit is None:
limit = n
start = (n + size - 1) // size
stop = min(limit, n - size + 1) + 1
for i in range(start, stop):
for tail in sum_to_n(n - i, size - 1, i):
yield [i] + tail
def consecutivegaps(n, leftmargin = 0, rightmargin = 0):
"""Compute all possible single consecutive gaps in any sequence of the specified length. Returns
(beginindex, length) tuples. Runs in O(n(n+1) / 2) time. Argument is the length of the sequence rather than the sequence itself"""
begin = leftmargin
while begin < n:
length = (n - rightmargin) - begin
while length > 0:
yield (begin, length)
length -= 1
begin += 1
def possiblesplits(n, minsplits=2, maxsplits=0):
"""Returns lists of (index,length) tuples, representing all possible splits of a sequence of length n."""
if not maxsplits: maxsplits = n
for nrsplits in range(minsplits,maxsplits + 1):
for split in sum_to_n(n,nrsplits):
split_with_indices = []
begin = 0
for length in split:
split_with_indices.append( (begin, length) )
begin += length
yield split_with_indices
def bytesize(n):
"""Return the required size in bytes to encode the specified integer"""
for i in range(1, 1000):
if n < 2**(8*i):
return i
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