Mapytex/random_expression.py

118 lines
3.3 KiB
Python

#!/usr/bin/env python
# encoding: utf-8
from random import randint
import re
class RdExpression(object):
"""A generator of random expression builder"""
def __init__(self, form, conditions = []):
"""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 {})
"""
self._form = form
self._conditions = conditions
self._letters = self.get_letters()
self._gene_varia = {}
self._gene_2replaced= {}
def get_2replaced(self):
"""Get elements of self._form which will have to be replaced
:returns: set for elements which have to be replaced
"""
pattern = "\{(.*?)\}" #select inside {} non greedy way
varia = re.findall(pattern, self._form)
varia = set(varia)
self._2replaced = varia
return varia
def get_letters(self):
"""Find letters in the form
:returns: list of letters
"""
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
def __call__(self, val_min = -10, val_max = 10):
"""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 random expression
"""
self.gene_varia(val_min, val_max)
while not(self.val_conditions()):
self.gene_varia(val_min, val_max)
return self._form.format(**self._gene_2replaced)
def gene_varia(self, val_min = -10, val_max = 10):
"""RAndomly generates variables/letters
"""
for l in self._letters:
self._gene_varia[l] = randint(val_min, val_max)
for e in self._2replaced:
self._gene_2replaced[e] = eval(e, globals(), self._gene_varia)
def val_conditions(self):
"""Tells whether or not conditions are validates
:returns: boolean
"""
if self._conditions != []:
return eval(" and ".join(self._conditions).format(**self._gene_varia))
else:
return True
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("Gene varia: ", rdExp._gene_varia)
print("Gene 2replaced: ", rdExp._gene_2replaced)
print('')
if __name__ == '__main__':
form = "{a}x + 2*{b}"
cond = ["{a} + {b} in [1, 2, 3, 4, 5]", "{a} not in [0,1]", "{b} not in [0,1]"]
rdExp1 = RdExpression(form, cond)
desc_rdExp(rdExp1)
rdExp2 = RdExpression(form)
desc_rdExp(rdExp2)
form = "{a+a/10}x + {a} + 2*{b}"
cond = ["{a} + {b} in [1, 2, 3, 4, 5]", "{a} not in [0,1]", "{b} not in [0,1]"]
rdExp3 = RdExpression(form)
desc_rdExp(rdExp3)
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