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sieve.py
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sieve.py
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# -*- coding: utf-8 -*-
# ------------------------------------------------------------------------------
# Name: sieve.py
# Purpose: sieve operations, after Iannis Xenakis.
#
# Authors: Christopher Ariza
#
# Copyright: Copyright © 2003, 2010 Christopher Ariza
# Copyright © 2010-2012, 19 Michael Scott Asato Cuthbert
# License: BSD, see license.txt
# ------------------------------------------------------------------------------
'''
A comprehensive, object model of the Xenakis Sieve. :class:`music21.sieve.Sieve`
objects can be created from high-level string notations, and used to generate line segments
in various representation. Additional functionality is available through associated objects.
The :class:`music21.sieve.Sieve` class permits generation segments in four formats.
>>> a = sieve.Sieve('3@2|7@1')
>>> a.segment()
[1, 2, 5, 8, 11, 14, 15, 17, 20, 22, 23, 26, 29, 32, 35, 36, 38, 41, 43, 44,
47, 50, 53, 56, 57, 59, 62, 64, 65, 68, 71, 74, 77, 78, 80, 83, 85, 86, 89, 92, 95, 98, 99]
>>> a.segment(segmentFormat='binary')
[0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1,
0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1,
0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1,
0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1]
>>> a.segment(segmentFormat='width')
[1, 3, 3, 3, 3, 1, 2, 3, 2, 1, 3, 3, 3, 3, 1, 2, 3, 2, 1, 3, 3, 3, 3, 1, 2, 3, 2,
1, 3, 3, 3, 3, 1, 2, 3, 2, 1, 3, 3, 3, 3, 1]
>>> len(a.segment(segmentFormat='unit'))
43
A :class:`music21.sieve.CompressionSegment` can be used to derive a Sieve from a
ny sequence of integers.
>>> a = sieve.CompressionSegment([3, 4, 5, 6, 7, 8, 13, 19])
>>> str(a)
'6@1|7@6|8@5|9@4|10@3|11@8'
The :class:`music21.sieve.PitchSieve` class provides a quick generation of
:class:`music21.pitch.Pitch` lists from Sieves.
>>> a = sieve.PitchSieve('13@3|13@6|13@9', 'c1', 'c10', 'f#4')
>>> pitches = a()
>>> ', '.join([str(p) for p in pitches])
'F#1, A1, C2, G2, B-2, C#3, G#3, B3, D4, A4, C5, E-5, B-5, C#6, E6, B6, D7,
F7, C8, E-8, F#8, C#9, E9, G9'
'''
from __future__ import annotations
from ast import literal_eval
from collections.abc import Iterable
import copy
from math import gcd, lcm
import random
import string
import typing as t
import unittest
from music21 import common
from music21 import environment
from music21 import exceptions21
from music21 import interval
from music21 import pitch
environLocal = environment.Environment('sieve')
# ------------------------------------------------------------------------------
class UnitException(exceptions21.Music21Exception):
pass
class ResidualException(exceptions21.Music21Exception):
pass
class SieveException(exceptions21.Music21Exception):
pass
class CompressionSegmentException(exceptions21.Music21Exception):
pass
class PitchSieveException(exceptions21.Music21Exception):
pass
LGROUP = '{'
RGROUP = '}'
AND = '&'
OR = '|'
XOR = '^'
BOUNDS = [LGROUP, RGROUP, AND, OR, XOR]
NEG = '-'
RESIDUAL = list(string.digits) + ['@']
# ------------------------------------------------------------------------------
# from
# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/117119
# David Eppstein, UC Irvine, 28 Feb 2002
# Alex Martelli
# other implementations
# http://c2.com/cgi-bin/wiki?SieveOfEratosthenesInManyProgrammingLanguages
# http://www.mycgiserver.com/~gpiancastelli/blog/archives/000042.html
def eratosthenes(firstCandidate=2):
'''
Yields the sequence of prime numbers via the Sieve of Eratosthenes.
rather than creating a fixed list of a range (z) and crossing out
multiples of sequential candidates, this algorithm stores primes under
their next possible candidate, thus allowing the generation of primes
in sequence without storing a complete range (z).
Create a dictionary. Each entry in the dictionary is a key:item pair of
(key) the largest multiple of this prime so far found and (item)
the prime. The dictionary only has as many entries as found primes.
If a candidate is not a key in the dictionary, it is not a multiple of
any already-found prime; it is thus a prime. a new entry is added to the
dictionary, with the square of the prime as the key. The square of the prime
is the next possible multiple to be found.
To use this generator, create an instance and then call the .next() method
on the instance.
>>> a = sieve.eratosthenes()
>>> next(a)
2
>>> next(a)
3
We can also specify a starting value for the sequence, skipping over
initial primes smaller than this number:
>>> a = sieve.eratosthenes(95)
>>> next(a)
97
>>> next(a)
101
'''
D = {} # map composite integers to primes witnessing their compositeness
# D stores largest composite: prime, pairs
q = 2 # candidate, first integer to test for primality
while True:
# get item from dict by key; remove from dict
# p is the prime, if already found
# q is the candidate, the running integer list
p = D.pop(q, None) # returns item for key, None if not in dict
# if candidate (q) is already in dict, not a prime
if p is not None: # key (prime candidate) in dictionary
# update dictionary w/ the next multiple of this prime not already
# in dictionary
nextMult = p + q # prime prime plus the candidate; next multiple
while nextMult in D: # incr x by p until it is a unique key
nextMult = nextMult + p
# re-store the prime under a key of the next multiple
D[nextMult] = p # x is now the next unique multiple to be found
# candidate (q) not already in dictionary; q is prime
else: # value not in dictionary
nextMult = q * q # square is next multiple tt will be found
D[nextMult] = q
if q >= firstCandidate:
yield q # return prime
q = q + 1 # incr. candidate
def rabinMiller(n):
'''
Returns True if an integer is likely prime or False if it is likely composite using the
Rabin Miller primality test.
See also here: http://www.4dsolutions.net/ocn/numeracy2.html
>>> sieve.rabinMiller(234)
False
>>> sieve.rabinMiller(5)
True
>>> sieve.rabinMiller(4)
False
>>> sieve.rabinMiller(97 * 2)
False
>>> sieve.rabinMiller(6 ** 4 + 1) # prime
True
>>> sieve.rabinMiller(123986234193) # divisible by 3, runs fast
False
'''
n = abs(n)
if n in (2, 3):
return True
m = n % 6 # if n (except 2 and 3) mod 6 is not 1 or 5, then n isn't prime
if m not in (1, 5):
return False
# primes up to 100; 2, 3 handled by mod 6
primes = [5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43,
47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
if n <= 100:
if n in primes:
return True # must include 2, 3
return False
for prime in primes:
if n % prime == 0:
return False
s, r = n - 1, 1
while not s & 1:
s >>= 1
r = r + 1
for i in range(10): # random tests
# calculate a^s mod n, where "a" is a random number
y = pow(random.randint(1, n - 1), s, n)
if y == 1: # pragma: no cover
continue # n passed test, is composite
# try values of j from 1 to r - 1
for j in range(1, r):
if y == n - 1:
break # if y = n - 1, n passed the test this time
y = pow(y, 2, n) # a^((2^j)*s) mod n
else: # pragma: no cover
return False # y never equaled n - 1, then n is composite
# n passed all the tests, it is very likely prime
return True
# ------------------------------------------------------------------------------
# list processing and unit interval routines
# possible move to common.py if used elsewhere
def discreteBinaryPad(series: Iterable[int], fixRange=None) -> list[int]:
'''
Treat a sequence of integers as defining contiguous binary integers,
where provided values are 1's and excluded values are zero.
For instance, running [3, 10, 12] through this method gives a 1 for
the first entry (signifying 3), 0s for the next six entries (signifying
4-9), a 1 (for 10), a 0 (for 11), and a 1 (for 12).
>>> sieve.discreteBinaryPad([3, 10, 12])
[1, 0, 0, 0, 0, 0, 0, 1, 0, 1]
>>> sieve.discreteBinaryPad([3, 4, 5])
[1, 1, 1]
'''
# make sure these are ints
for x in series:
if not common.isNum(x):
raise UnitException('non-integer value found')
discrete = []
if fixRange is not None:
fixRange.sort() # make sure sorted
minVal = fixRange[0]
maxVal = fixRange[-1]
else: # find max and min from values
seriesAlt = list(copy.deepcopy(series))
seriesAlt.sort()
minVal = seriesAlt[0]
maxVal = seriesAlt[-1]
for x in range(minVal, maxVal + 1):
if x in series:
discrete.append(1)
else: # not in series
discrete.append(0)
return discrete
def unitNormRange(series, fixRange=None):
'''
Given a list of numbers, create a proportional spacing across the unit interval.
The first entry will always be 0 and the last 1, other entries will be spaced
according to their distance between these two units. For instance, for 0, 3, 4
the middle entry will be 0.75 since 3 is 3/4 of the distance between 0 and 4:
>>> sieve.unitNormRange([0, 3, 4])
[0.0, 0.75, 1.0]
but for [1, 3, 4], it will be 0.666... because 3 is 2/3 of the distance between
1 and 4
>>> sieve.unitNormRange([1, 3, 4])
[0.0, 0.666..., 1.0]
'''
if fixRange is not None:
fixRange.sort()
minFound = fixRange[0]
maxFound = fixRange[-1]
else: # find maxFound and minFound from values
minFound = min(series)
maxFound = max(series)
span = maxFound - minFound
unit = []
if len(series) > 1:
for val in series:
dif = val - minFound
if common.isNum(dif):
dif = float(dif)
if span != 0:
unit.append(dif / span)
else: # fill value if span is zero
unit.append(0)
else: # if one element, return 0 (could be 1, or 0.5)
unit.append(0)
return unit
def unitNormEqual(parts):
'''
Given a certain number of parts, return a list unit-interval values
between 0 and 1, with as many divisions as parts; 0 and 1 are always inclusive.
>>> sieve.unitNormEqual(3)
[0.0, 0.5, 1]
If parts is 0 or 1, then a single entry of [0] is given:
>>> sieve.unitNormEqual(1)
[0]
'''
if parts <= 1:
return [0]
elif parts == 2:
return [0, 1]
else:
unit = []
step = 1 / (parts - 1)
for y in range(parts - 1): # one less value tn needed
unit.append(y * step)
unit.append(1) # make last an integer, add manually
return unit
def unitNormStep(step, a=0, b=1, normalized=True):
'''
Given a step size and an a/b min/max range, calculate number of parts
to fill step through inclusive a,b, then return a unit interval list of values
necessary to cover region.
Note that returned values are, by default, normalized within the unit interval.
>>> sieve.unitNormStep(0.5, 0, 1)
[0.0, 0.5, 1]
>>> sieve.unitNormStep(0.5, -1, 1)
[0.0, 0.25, 0.5, 0.75, 1]
>>> sieve.unitNormStep(0.5, -1, 1, normalized=False)
[-1, -0.5, 0.0, 0.5, 1.0]
>>> post = sieve.unitNormStep(0.25, 0, 20)
>>> len(post)
81
>>> post = sieve.unitNormStep(0.25, 0, 20, normalized=False)
>>> len(post)
81
'''
if a == b:
return [] # no range, return boundary
if a < b:
minVal = a
maxVal = b
else:
minVal = b
maxVal = a
# find number of parts necessary
count = 0 # will count last, so do not count min at beginning
values = []
x = minVal
while x <= maxVal:
values.append(x) # do before incrementing
x += step
count += 1
if normalized:
return unitNormEqual(count)
else:
return values
# ------------------------------------------------------------------------------
# note: some of these methods are in common, though they are slightly different algorithms;
# need to test for compatibility
def _meziriac(c1, c2):
# Bachet de Meziriac (1624)
# in order for x and y to be two coprimes, it is necessary and sufficient
# that there exist two relative whole numbers, e, g such that
# 1 + (g * x) = e * y or
# y' * x = (e' * y) + 1
# where e and g come from the recursive equations
# (e * c2) % c1 == 1 and
# (g'* c1) % c2 == 1 ### this is version used here
# while letting e, g' run through values 0, 1, 2, 3...
# except if c1 == 1 and c2 == 1
g = 0
if c2 == 1:
g = 1
elif c1 == c2:
g = 0 # if equal, causes infinite loop of 0
else:
while g < 10000:
val = (g * c1) % c2
if val == 1:
break
g = g + 1
return g
# ------------------------------------------------------------------------------
class PrimeSegment:
def __init__(self, start, length):
'''
A generator of prime number segments, given a start value
and desired length of primes.
>>> ps = sieve.PrimeSegment(3, 20)
>>> ps()
[3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73]
'''
self.seg = []
self.start = start
self.length = length
# fill the segment
self._fillRange()
def _fillRabinMiller(self, start, length, stop=None, direction='up'):
'''
scan all number in range and return a list of primes
provide a max to force stoppage at certain point before the
maximum length
direction determines which way things go.
'''
seg = []
_oddBoundary = 4 # number above which only odd primes are found
if start % 2 == 0 and start > _oddBoundary: # if even
if direction == 'up':
n = start + 1
else: # if down
n = start - 1
else:
n = start
while 1:
if rabinMiller(n):
seg.append(n)
if len(seg) >= length:
break
if n == stop:
break
if n > _oddBoundary: # after 5, no even primes
if direction == 'up':
n = n + 2 # only test odd numbers
else:
n = n - 2
else: # n is less than 5, add 1
if direction == 'up':
n = n + 1 # must increment by 1
else:
n = n - 1
return seg
def _fillRange(self):
'''
fill positive and negative range
'''
if self.start < 0:
# create the negative portion of the segment
segNeg = self._fillRabinMiller(abs(self.start), self.length, 0, 'down')
segNeg = [-x for x in segNeg] # make negative
if len(segNeg) < self.length:
segPos = self._fillRabinMiller(0, self.length - len(segNeg),
None, 'up')
self.seg = segNeg + segPos
else: # add positive values
self.seg = segNeg
else: # start from zero alone
self.seg = self._fillRabinMiller(self.start, self.length, None, 'up')
def __call__(self, segmentFormat=None):
'''
assumes that min and max values are derived from found primes
means that primes will always be at boundaries
'''
z = [self.seg[0], self.seg[-1]]
if segmentFormat in ('bin', 'binary'):
return discreteBinaryPad(self.seg, z)
elif segmentFormat == 'unit':
return unitNormRange(self.seg, z)
elif segmentFormat in ('wid', 'width'):
wid = []
for i in range(len(self.seg) - 1):
wid.append((self.seg[i + 1] - self.seg[i]))
return wid
else: # int, integer
return self.seg
# ------------------------------------------------------------------------------
class Residual:
'''
object that represents a modulus and a start point
each object stores a range of integers (self._z) from which sections are drawn
this range of integers can be changed whenever the section os drawn
>>> residual = sieve.Residual(3, 2)
'''
def __init__(self, m, shift=0, neg=0, z=None):
# get a default range, can be changed later
# is an actual range and not start/end points b/c when producing a not (-)
# it is easy to remove the mod,n from the range
if z is None: # supply default if necessary
z = list(range(100))
self._z = z
# print('residual init self._z', self._z)
self._m = m
if neg not in (0, 1):
raise ResidualException('negative value must be 0, 1, or a Boolean')
self._neg = neg # negative, complement boolean
if self._m == 0: # 0 mode causes ZeroDivisionError
self._shift = shift
else:
self._shift = shift % self._m # do mod on shift
self._segmentFormatOptions = ['int', 'bin', 'unit', 'wid']
self._segmentFormat = 'int'
# --------------------------------------------------------------------------
# utility functions
def setZ(self, z):
'''
z is the range of integers to use when generating a list
'''
self._z = z
def setZRange(self, minInt, maxInt):
'''
z is the range of integers to use when generating a list
convenience function that fixes max
'''
self._z = list(range(minInt, maxInt + 1))
def setSegmentFormat(self, fmt):
# fmt = drawer.strScrub(fmt, 'l')
fmt = fmt.strip().lower()
if fmt in self._segmentFormatOptions:
raise ResidualException(f'format not in format options: {fmt}')
self._segmentFormat = fmt
# --------------------------------------------------------------------------
def segment(self, n=0, z=None, segmentFormat=None):
'''
get a residual subset of this modulus at this n
within the integer range provided by z
format can be 'int' or 'bin', for integer or binary
>>> a = sieve.Residual(3, 2)
>>> a.segment(3)
[2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47, 50, 53, 56, 59,
62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 92, 95, 98]
>>> a.segment(3, range(3, 15))
[5, 8, 11, 14]
'''
if z is None: # z is temporary; if none
z = self._z # assign to local
if segmentFormat is None:
segmentFormat = self._segmentFormat
subset = []
if self._m == 0:
return subset # empty
n = (n + self._shift) % self._m # check for n >= m
for value in z:
if n == value % self._m:
subset.append(value)
if self._neg: # find opposite
compSet = copy.deepcopy(z)
for value in subset:
compSet.remove(value)
seg = compSet
else:
seg = subset
if segmentFormat in ('bin', 'binary'):
return discreteBinaryPad(seg, z)
elif segmentFormat == 'unit':
return unitNormRange(seg, z)
elif segmentFormat in ('wid', 'width'): # difference always equal to m
wid = [self._m] * (len(seg) - 1) # one shorter than segment
return wid
elif segmentFormat in ('int', 'integer'): # int, integer
return seg
else:
raise ResidualException(f'{segmentFormat} not a valid sieve segmentFormat string.')
def period(self) -> int:
'''
period is M; obvious, but nice for completeness
>>> a = sieve.Residual(3, 2)
>>> a.period()
3
'''
return self._m
# --------------------------------------------------------------------------
def copy(self):
# TODO: replace with deepcopy method
m = copy.copy(self._m)
shift = copy.copy(self._shift)
neg = copy.copy(self._neg)
# provide ref, not copy, to z
return Residual(m, shift, neg, self._z)
def __call__(self, n=0, z=None, segmentFormat=None):
'''
calls self.segment(); uses _segmentFormat
>>> a = sieve.Residual(3, 2)
>>> a()
[2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47,
50, 53, 56, 59, 62, 65, 68, 71, 74, 77, 80, 83, 86, 89, 92, 95, 98]
'''
# if z is None, uses self._z
return self.segment(n, z, segmentFormat)
def represent(self, style=None):
'''
does not show any logical operator but unary negation
'''
if style == 'classic': # mathematical style
if self._shift != 0:
repStr = f'{self._m}(n+{self._shift})'
else:
repStr = f'{self._m}(n)'
if self._neg:
repStr = f'-{repStr}'
else: # do evaluatable type
repStr = f'{self._m}@{self._shift}' # show w/ @
if self._neg:
repStr = f'-{repStr}'
return repStr
def __str__(self):
'''
str representation using M(n + shift) style notation
>>> a = sieve.Residual(3, 2)
>>> str(a)
'3@2'
'''
return self.represent() # default style
def __eq__(self, other):
'''
==, compare residual classes in terms of m and shift
'''
if other is None:
return 0
if (self._m == other._m
and self._shift == other._shift
and self._neg == other._neg):
return 1
else:
return 0
def __cmp__(self, other):
'''
allow comparison based on m and shift; if all equal look at neg
Still being used internally even though __cmp__ is not used in Python 3
'''
# return neg if self < other, zero if self == other,
# a positive integer if self > other.
if self._m < other._m:
return -1
elif self._m > other._m:
return 1
# if equal compare shift
elif self._m == other._m:
if self._shift < other._shift:
return -1
elif self._shift > other._shift:
return 1
else: # shifts are equal
if self._neg != other._neg:
if self._neg == 1: # its negative, then less
return -1
else:
return 1
else:
return 0
def __lt__(self, other):
if self.__cmp__(other) == -1:
return True
else:
return False
def __gt__(self, other):
if self.__cmp__(other) == 1:
return True
else:
return False
def __neg__(self):
'''
unary neg operators; return neg object
'''
if self._neg: # if 1
neg = 0
else: # if 0
neg = 1
return Residual(self._m, self._shift, neg, self._z)
def __and__(self, other):
'''
&, produces an intersection of two Residual classes
returns a new Residual class
cannot be done if R under complementation
>>> a = sieve.Residual(3, 2)
>>> b = sieve.Residual(5, 1)
>>> c = a & b
>>> str(c)
'15@11'
'''
if other._neg or self._neg:
raise ResidualException('complemented Residual objects cannot be intersected')
m, n = self._cmpIntersection(self._m, other._m, self._shift, other._shift)
# get the union of both z
zSet = set(self._z) | set(other._z)
z = list(zSet)
# neg = 0 # most not be complemented
return Residual(m, n, 0, z)
def __or__(self, other):
'''
|, not sure if this can be implemented
i.e., a union of two Residual classes can not be expressed as a single
Residual, that is intersections can always be reduced, whereas unions
cannot be reduced.
'''
pass
# --------------------------------------------------------------------------
def _cmpIntersection(self, m1, m2, n1, n2):
'''
compression by intersection
find m,n such that the intersection of two Residuals can
be reduced to one Residual. Xenakis p 273.
'''
d = gcd(m1, m2)
c1 = m1 // d # not sure if we need floats here
c2 = m2 // d
n3 = 0
m3 = 0
if m1 != 0 and m2 != 0:
n1 = n1 % m1
n2 = n2 % m2
else: # one of the mods is equal to 0
return n3, m3 # no intersection
if d != 1 and ((n1 - n2) % d != 0):
return n3, m3 # no intersection
elif d != 1 and ((n1 - n2) % d == 0) and (n1 != n2) and (c1 == c2):
m3 = d # for real?
n3 = n1
return m3, n3
else: # d == 1, or ...
m3 = c1 * c2 * d
g = _meziriac(c1, c2) # c1,c2 must be co-prime may produce a loop
n3 = (n1 + (g * (n2 - n1) * c1)) % m3
return m3, n3
# ------------------------------------------------------------------------------
class CompressionSegment:
'''
Utility to convert from a point sequence to sieve.
A z range can be supplied to explicitly provide the complete sieve segment,
both positive and negative values. all values in the z range not in the
segment are interpreted as negative values. thus, there is an essential
dependency on the z range and the realized sieve.
No matter the size of the z range, there is a modulus at which one point
in the segment can be found. As such, any segment can be reduced to, at a
minimum, a residual for each point in the segment, each, for the supplied z,
providing a segment with one point.
The same segment can then have multiplied logical string representations,
depending on the provided z.
>>> a = sieve.CompressionSegment([3, 4, 5, 6, 7, 8, 13, 19])
>>> str(a)
'6@1|7@6|8@5|9@4|10@3|11@8'
>>> b = sieve.CompressionSegment([0, 2, 4, 6, 8])
>>> str(b)
'2@0'
>>> c = sieve.CompressionSegment([0, 2, 4, 5, 7, 9, 11, 12])
>>> str(c)
'5@2|5@4|6@5|7@0'
'''
def __init__(self, src, z=None):
# The supplied list of values is only the positive values of a sieve segment
# we do not know what the negative values are; we can assume they are between
# the min and max of the list, but this may not be true in all cases.
src = list(copy.deepcopy(src))
src.sort()
self._match = [] # already sorted from src
for num in src: # remove redundancies
if num not in self._match:
self._match.append(num)
if len(self._match) <= 1:
raise CompressionSegmentException('segment must have more than one element')
self._zUpdate(z) # sets self._z
# max mod should always be the max of z; this is b/c at for any segment
# if the mod == max of seg, at least one point can be found in the segment
# mod is the step size, so only one step will happen in the sequence
self._maxMod = len(self._z) # set maximum mod tried
# assign self._residuals and do analysis
try:
self._process()
except AssertionError:
raise CompressionSegmentException('no Residual classes found for this z range')
def _zUpdate(self, z=None):
# z must at least be a superset of match
if z is not None: # it is a list
if not self._subset(self._match, z):
raise CompressionSegmentException(
'z range must be a superset of desired segment')
self._z = z
zMin, zMax = self._z[0], self._z[-1]
# z is range from max to min, unless provided at init
else: # range from min, max; add 1 for range() to max
zMin, zMax = self._match[0], self._match[-1]
self._z = list(range(zMin, (zMax + 1)))
# --------------------------------------------------------------------------
def __call__(self):
'''
>>> a = sieve.CompressionSegment([3, 4, 5, 6, 7, 8])
>>> b = a()
>>> str(b[0])
'1@0'
'''
return self._residuals
def __str__(self):
resStr = []
if len(self._residuals) == 1: # single union must have an or
resStr = str(self._residuals[0])
else:
for resObj in self._residuals:
resStr.append(str(resObj))
resStr = '|'.join(resStr)
return resStr
# --------------------------------------------------------------------------
def _subset(self, sub, thisSet):
'''
True if sub is part of set; assumes no redundancies in each
'''
commonNum = 0
for x in sub:
if x in thisSet:
commonNum = commonNum + 1
if commonNum == len(sub):
return 1
else:
return 0
def _find(self, n, part, whole):
'''
given a point, and SieveSegment, find a modulus and shift that
match.
'''
m = 1 # could start at one, but only pertains to the single case of 1@0
while m < self._maxMod: # search m for max
obj = Residual(m, n, 0, self._z)
seg = obj() # n, z is set already
# check first to see if it is a member of the part
if self._subset(seg, part):
return obj, seg
elif self._subset(seg, whole):
return obj, seg
m = m + 1
# a mod will always be found, at least 1 point; should never happen
raise SieveException(f'a mod was not found less than {self._maxMod}')
def _process(self):
'''
take a copy of match; move through each value of this list as if it
were n; for each n test each modulo (from 1 to len(z) + 1) to find a
residual. when found (one will be found), keep it; remove the found
segments from the match, and repeat.
'''
# process residuals
self._residuals = [] # list of objects
match = copy.copy(self._match) # scratch to work on
maxToRun = 10000
while maxToRun: # loop over whatever is left in the match copy
maxToRun -= 1
n = match[0] # always get first item
obj, seg = self._find(n, match, self._match)
if obj is None: # no residual found; should never happen
raise CompressionSegmentException('_find() returned a None object')
if obj not in self._residuals: # b/c __eq__ defined
self._residuals.append(obj)
for x in seg: # clean found values from match
if x in match:
match.remove(x)
if not match:
break
self._residuals.sort()
# ------------------------------------------------------------------------------
# http://docs.python.org/lib/set-objects.html
# set object precedence: & before |
# >>> a = set([3, 4])
# >>> b = set([4, 5])
# >>> c = set([3, 4, 5])
# >>> a & b & c
# Set([4])
# >>> a & b | c
# Set([3, 4, 5])
# >>> a & (b | c)
# Set([3, 4])
# >>> (a & b) | c
# Set([3, 4, 5])
# >>> b = sieve.SieveBound('2&4&8|5')
# <R0>&<R1>&<R2>|<R3>
# >>> str(b)
# '2&4&8|5'
# >>> b(0, range(20))
# [0, 5, 8, 10, 15, 16]
# >>> b = sieve.SieveBound('2&4&(8|5)')
# <R0>&<R1>&(<R2>|<R3>)
# >>> b(0, range(20))
# [0, 8, 16]
# >>> b = sieve.SieveBound('5|2&4&8')
# <R0>|<R1>&<R2>&<R3>
# >>> b(0, range(20))
# [0, 5, 8, 10, 15, 16]
# >>> b = sieve.SieveBound('(5|2)&4&8')
# (<R0>|<R1>)&<R2>&<R3>
# >>> b(0, range(20))
# [0, 8, 16]
# >>>