Mapytex/pymath/expression.py

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#!/usr/bin/env python
# encoding: utf-8
from .generic import Stack, flatten_list, expand_list, isNumber, isOperator
from .render import txt, tex
from .str2tokens import str2tokens
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from .operator import op
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from .random_expression import RdExpression
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__all__ = ['Expression']
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class Expression(object):
"""A calculus expression. Today it can andle only expression with numbers later it will be able to manipulate unknown"""
STR_RENDER = tex
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DEFAULT_RENDER = tex
@classmethod
def set_render(cls, render):
cls.STR_RENDER = render
@classmethod
def set_df_render(cls):
cls.set_render(cls.DEFAULT_RENDER)
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@classmethod
def random(self, form="", conditions=[], val_min = -10, val_max=10):
"""Create a random expression from form and with conditions
:param form: the form of the expression (/!\ variables need to be in brackets {})
:param conditions: condition on variables (/!\ variables need to be in brackets {})
:param val_min: min value for generate variables
:param val_max: max value for generate variables
"""
random_generator = RdExpression(form, conditions)
return Expression(random_generator(val_min, val_max))
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def __init__(self, exp):
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""" Initiate the expression
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:param exp: the expression. It can be a string or a list of postfix tokens.
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"""
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if type(exp) == str:
#self._exp = exp
self.postfix_tokens = str2tokens(exp) # les tokens seront alors stockés dans self.tokens temporairement
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elif type(exp) == list:
self.postfix_tokens = flatten_list([tok.postfix_tokens if self.isExpression(tok) else tok for tok in exp])
self._isExpression = 1
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def __str__(self):
"""
Overload str
If you want to changer render set Expression.RENDER
"""
return self.STR_RENDER(self.postfix_tokens)
def __repr__(self):
return "< Expression " + str(self.postfix_tokens) + ">"
def render(self, render = lambda x:str(x)):
""" Same as __str__ but accept render as argument
:param render: function which render the list of token (postfix form) to string
"""
# TODO: I don't like the name of this method |ven. janv. 17 12:48:14 CET 2014
return render(self.postfix_tokens)
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## ---------------------
## Mechanism functions
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def simplify(self):
""" Generator which return steps for computing the expression """
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if not self.can_go_further():
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yield self.STR_RENDER(self.postfix_tokens)
else:
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self.compute_exp()
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old_s = ''
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for s in self.steps:
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new_s = self.STR_RENDER(s)
# Astuce pour éviter d'avoir deux fois la même étape (par exemple pour la transfo d'une division en fraction)
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if new_s != old_s:
old_s = new_s
yield new_s
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for s in self.child.simplify():
if old_s != s:
yield s
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def simplified(self):
""" Get the simplified version of the expression """
if not self.can_go_further():
return self.postfix_tokens[0]
else:
return self.child.simplified()
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def can_go_further(self):
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"""Check whether it's a last step or not. If not create self.child the next expression.
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:returns: 1 if it's not the last step, 0 otherwise
"""
if len(self.postfix_tokens) == 1:
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return 0
else:
return 1
def compute_exp(self):
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""" Create self.child with self.steps to go up to it """
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self.steps = [self.postfix_tokens]
tokenList = self.postfix_tokens.copy()
tmpTokenList = []
while len(tokenList) > 2:
# on va chercher les motifs du genre A B +, quand l'operateur est d'arité 2, pour les calculer
if isNumber(tokenList[0]) and isNumber(tokenList[1]) \
and isOperator(tokenList[2]) and tokenList[2].arity == 2 :
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# S'il y a une opération à faire
op1 = tokenList[0]
op2 = tokenList[1]
operator = tokenList[2]
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res = operator(op1, op2)
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tmpTokenList.append(res)
# Comme on vient de faire le calcul, on peut détruire aussi les deux prochains termes
del tokenList[0:3]
# Et les motifs du gens A -, quand l'operateur est d'arité 1
elif isNumber(tokenList[0]) \
and isOperator(tokenList[1]) and tokenList[1].arity == 1:
# S'il y a une opération à faire
op1 = tokenList[0]
operator = tokenList[1]
res = operator(op1)
tmpTokenList.append(res)
# Comme on vient de faire le calcul, on peut détruire aussi les deux prochains termes
del tokenList[0:2]
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else:
tmpTokenList.append(tokenList[0])
del tokenList[0]
tmpTokenList += tokenList
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steps = expand_list(tmpTokenList)
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if len(steps[:-1]) > 0:
self.steps += [flatten_list(s) for s in steps[:-1]]
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self.child = Expression(steps[-1])
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def isExpression(self, other):
try:
other._isExpression
except AttributeError:
return 0
return 1
# -----------
# Some math manipulations
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def operate(self, other, operator):
if type(other) == Expression:
return Expression(self.postfix_tokens + other.postfix_tokens + [operator])
elif type(other) == list:
return Expression(self.postfix_tokens + other + [operator])
else:
return Expression(self.postfix_tokens + [other] + [operator])
def roperate(self, other, operator):
if type(other) == Expression:
return Expression(other.postfix_tokens + self.postfix_tokens + [operator])
elif type(other) == list:
return Expression(other + self.postfix_tokens + [operator])
else:
return Expression([other] + self.postfix_tokens + [operator])
def __add__(self, other):
return self.operate(other, op.add)
def __radd__(self, other):
return self.roperate(other, op.add)
def __sub__(self, other):
return self.operate(other, op.sub)
def __rsub__(self, other):
return self.roperate(other, op.sub)
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def __mul__(self, other):
return self.operate(other, op.mul)
def __rmul__(self, other):
return self.roperate(other, op.mul)
def __div__(self, other):
return self.operate(other, op.div)
def __rdiv__(self, other):
return self.roperate(other, op.div)
def __pow__(self, other):
return self.operate(other, op.pow)
def __neg__(self):
return Expression(self.postfix_tokens + [op.sub1])
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def test(exp):
a = Expression(exp)
print(a)
for i in a.simplify():
print(i)
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print(type(a.simplified()), ":", a.simplified())
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print("\n")
if __name__ == '__main__':
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Expression.set_render(txt)
exp1 = "2 ^ 3 * 5"
test(exp1)
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Expression.set_render(tex)
test(exp1)
from pymath.operator import op
exp = [2, 3, op.pw, 5, op.mul]
test(exp)
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Expression.set_render(txt)
test([Expression(exp1), Expression(exp), op.add])
exp = "1 + 3 * 5"
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e = Expression(exp)
f = -e
print(f)
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#exp = "2 * 3 * 3 * 5"
#test(exp)
#exp = "2 * 3 + 3 * 5"
#test(exp)
#exp = "2 * ( 3 + 4 ) + 3 * 5"
#test(exp)
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#exp = "2 * ( 3 + 4 ) + ( 3 - 4 ) * 5"
#test(exp)
#
#exp = "2 * ( 2 - ( 3 + 4 ) ) + ( 3 - 4 ) * 5"
#test(exp)
#
#exp = "2 * ( 2 - ( 3 + 4 ) ) + 5 * ( 3 - 4 )"
#test(exp)
#
#exp = "2 + 5 * ( 3 - 4 )"
#test(exp)
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#exp = "( 2 + 5 ) * ( 3 - 4 )^4"
#test(exp)
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#exp = "( 2 + 5 ) * ( 3 * 4 )"
#test(exp)
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#exp = "( 2 + 5 - 1 ) / ( 3 * 4 )"
#test(exp)
#exp = "( 2 + 5 ) / ( 3 * 4 ) + 1 / 12"
#test(exp)
#exp = "( 2+ 5 )/( 3 * 4 ) + 1 / 2"
#test(exp)
#exp="(-2+5)/(3*4)+1/12+5*5"
#test(exp)
#exp="-2*4(12 + 1)(3-12)"
#test(exp)
#exp="(-2+5)/(3*4)+1/12+5*5"
#test(exp)
# TODO: The next one doesn't work |ven. janv. 17 14:56:58 CET 2014
#exp="-2*(-a)(12 + 1)(3-12)"
#e = Expression(exp)
#print(e)
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## Can't handle it yet!!
#exp="-(-2)"
#test(exp)
print("\n")
exp = Expression.random("({a} + 3)({b} - 1)", ["{a} > 4"])
for i in exp.simplify():
print(i)
#import doctest
#doctest.testmod()
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# -----------------------------
# Reglages pour 'vim'
# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
# cursor: 16 del