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94 lines
2.9 KiB
Plaintext
94 lines
2.9 KiB
Plaintext
###########################################################
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# RapydScript Standard Library
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# Author: Alexander Tsepkov
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# Copyright 2013 Pyjeon Software LLC
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# License: Apache License 2.0
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# This library is covered under Apache license, so that
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# you can distribute it with your RapydScript applications.
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###########################################################
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# basic implementation of Python's 'random' library
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# JavaScript's Math.random() does not allow seeding its random generator, to bypass that, this module implements its own
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# version that can be seeded. I decided on RC4 algorithm for this.
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# please don't mess with this from the outside
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ρσ_seed_state = {
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'key': [],
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'key_i': 0,
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'key_j': 0
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}
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ρσ_get_random_byte = def():
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ρσ_seed_state.key_i = (ρσ_seed_state.key_i + 1) % 256
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ρσ_seed_state.key_j = (ρσ_seed_state.key_j + ρσ_seed_state.key[ρσ_seed_state.key_i]) % 256
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ρσ_seed_state.key[ρσ_seed_state.key_i], ρσ_seed_state.key[ρσ_seed_state.key_j] = \
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ρσ_seed_state.key[ρσ_seed_state.key_j], ρσ_seed_state.key[ρσ_seed_state.key_i]
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return ρσ_seed_state.key[(ρσ_seed_state.key[ρσ_seed_state.key_i] + \
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ρσ_seed_state.key[ρσ_seed_state.key_j]) % 256]
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def seed(x=Date().getTime()):
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if jstype(x) is 'number':
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x = x.toString()
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elif jstype(x) is not 'string':
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raise TypeError("unhashable type: '" + jstype(x) + "'")
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for i in range(256):
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ρσ_seed_state.key[i] = i
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j = 0
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for i in range(256):
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j = (j + ρσ_seed_state.key[i] + x.charCodeAt(i % x.length)) % 256
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ρσ_seed_state.key[i], ρσ_seed_state.key[j] = ρσ_seed_state.key[j], ρσ_seed_state.key[i]
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seed()
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def random():
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n = 0
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m = 1
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for i in range(8):
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n += ρσ_get_random_byte() * m
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m *= 256
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return n / 18446744073709551616
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# unlike the python version, this DOES build a range object, feel free to reimplement
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def randrange():
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return choice(range.apply(this, arguments))
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def randint(a, b):
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return int(random()*(b-a+1) + a)
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def uniform(a, b):
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return random()*(b-a) + a
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def choice(seq):
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if seq.length > 0:
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return seq[Math.floor(random()*seq.length)]
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else:
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raise IndexError()
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# uses Fisher-Yates algorithm to shuffle an array
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def shuffle(x, random_f=random):
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for i in range(x.length):
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j = Math.floor(random_f() * (i+1))
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x[i], x[j] = x[j], x[i]
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return x
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# similar to shuffle, but only shuffles a subset and creates a copy
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def sample(population, k):
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x = population.slice()
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for i in range(population.length-1, population.length-k-1, -1):
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j = Math.floor(random() * (i+1))
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x[i], x[j] = x[j], x[i]
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return x.slice(population.length-k)
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#import stdlib
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#a = range(50)
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#random.seed(5)
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#print(random.choice(a))
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#print(random.shuffle(a))
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#print(random.randrange(10))
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#print(random.randint(1,5))
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#print(random.uniform(1,5))
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#print(random.sample(range(20),5))
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