Mapytex/pymath/calculus/random_expression.py

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#!/usr/bin/env python
# encoding: utf-8
from random import randint
import re
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import pyparsing
from .generic import flatten_list
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from .arithmetic import gcd
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def random_str(form, conditions = [], val_min = -10, val_max = 10):
""" Create a random string using RdExpression class """
random_str_generator = RdExpression(form, conditions)
return random_str_generator(val_min, val_max)
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class RdExpression(object):
"""
A generator of random expression builder
"""
def __init__(self, form, conditions = []):
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"""Initiate the generator
:param form: the form of the expression (/!\ variables need to be in brackets {})
:param conditions: condition on variables (/!\ variables need to be in brackets {})
"""
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self._form = self.mod_underscores(form)
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self._conditions = conditions
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self._letters = self.get_letters()
self._gene_varia = {}
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self._gene_2replaced = {}
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def get_2replaced(self):
"""Get elements of self._form which will have to be replaced
:returns: set for elements which have to be replaced
"""
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#pattern = "\{(.*?)\}" #select inside {} non greedy way
#varia_form = re.findall(pattern, self._form)
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# TODO: Bug with varia with spaces |dim. nov. 23 10:44:34 CET 2014
varia_form = flatten_list([eval(str(i[0])) for i in pyparsing.nestedExpr('{','}').searchString(self._form)])
varia_form = set(varia_form)
varia_cond = set()
for c in self._conditions:
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c_varia_cond = flatten_list([eval(str(i[0])) for i in pyparsing.nestedExpr('{','}').searchString(c)])
varia_cond = varia_cond | set(c_varia_cond)
self._2replaced = varia_cond | varia_form
return self._2replaced
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def get_letters(self):
"""Find letters in the form
:returns: list of letters
"""
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v2replaced = self.get_2replaced()
varia = set()
pattern = "([a-zA-Z]+)"
for v in v2replaced:
lvar = set(re.findall(pattern, v))
varia = varia | lvar
return varia
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def mod_underscores(self, form):
""" Transform underscores of string to {...} forme with capital letters
:param form: the form string with _ to replace
:returns: the string with _ replaced
"""
i = 64
new_form = form
while "_" in new_form:
i += 1
new_form = new_form.replace("_", "{"+chr(i)+"}",1)
return new_form
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def __call__(self, val_min = -10, val_max = 10):
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"""RdExpression once it is initiate act like a function which create random expressions.
:param val_min: minimum value random generation
:param val_max: maximum value random generation
:returns: an formated random expression
"""
return self.raw_str(val_min, val_max)
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def raw_str(self, val_min = -10, val_max = 10):
"""Return raw string (don't use Expression for rendering or parsing)
:param val_min: minimum value random generation
:param val_max: maximum value random generation
:returns: an random Expression object
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"""
self.gene_varia(val_min, val_max)
while not(self.val_conditions()):
self.gene_varia(val_min, val_max)
exp = self._form.format(**self._gene_2replaced)
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return exp
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def gene_varia(self, val_min = -10, val_max = 10):
"""Randomly generates variables/letters
Varia can't be equal to 0
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"""
for l in self._letters:
self._gene_varia[l] = randint(val_min, val_max)
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while self._gene_varia[l] == 0:
self._gene_varia[l] = randint(val_min, val_max)
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for e in self._2replaced:
self._gene_2replaced[e] = eval(e, globals(), self._gene_varia)
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def val_conditions(self):
"""Tells whether or not conditions are validates
:returns: boolean
"""
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if self._conditions != []:
return eval(" and ".join(self._conditions).format(**self._gene_2replaced))
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else:
return True
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def desc_rdExp(rdExp):
print("--------------------")
print("form: ",rdExp._form)
print("Conditions: ",rdExp._conditions)
print("Letters: ", rdExp._letters)
print("2replaced: ", rdExp._2replaced)
print("Call : ", rdExp())
print("type: ",type(rdExp()))
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print("Gene varia: ", rdExp._gene_varia)
print("Gene 2replaced: ", rdExp._gene_2replaced)
print('')
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if __name__ == '__main__':
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form = "({a};{b})"
cond = []
print(random_str(form, cond))
form = "{a+a*10}*4 + {a} + 2*{b}"
cond = ["{a} + {b} in [1, 2, 3, 4, 5]", "abs({a}) not in [1]", "{b} not in [1]", "gcd({a},{b}) == 1"]
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print(random_str(form, cond))
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form = "{a+a*10}*4 + {a} + 2*{b}"
cond = ["{a-b} + {b} in list(range(20))", "abs({a}) not in [1]", "{b} not in [1]", "gcd({a},{b}) == 1"]
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print(random_str(form, cond))
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import doctest
doctest.testmod()
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# -----------------------------
# Reglages pour 'vim'
# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
# cursor: 16 del