Mapytex/calculus.py

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#!/usr/bin/env python
# encoding: utf-8
from generic import Stack
def infixToPostfix(infixExp):
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"""Transform an infix expression into postfix expression
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:param infixExp: an infix expression (caracters must be separate by a space)
:returns: the corresponding postfix expression
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:Example:
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>>> infixToPostfix("1 + 2")
'1 2 +'
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>>> infixToPostfix("1 * 2 + 3")
'1 2 * 3 +'
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"""
priority = {"*" : 3, "/": 3, "+": 2, "-":2, "(": 1}
opStack = Stack()
postfixList = []
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tokenList = infixExp.split(" ")
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for token in tokenList:
if token == "(":
opStack.push(token)
elif token == ")":
topToken = opStack.pop()
while topToken != "(":
postfixList.append(topToken)
topToken = opStack.pop()
elif token in "+-*/":
while (not opStack.isEmpty()) and (priority[opStack.peek()] >= priority[token]):
postfixList.append(opStack.pop())
opStack.push(token)
else:
postfixList.append(token)
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while not opStack.isEmpty():
postfixList.append(opStack.pop())
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return " ".join(postfixList)
def computePostfix(postfixExp):
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"""Compute a postfix expression
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:param postfixExp: a postfix expression
:returns: the result of the expression
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"""
print(postfixToInfix(postfixExp))
# where to save numbers or
operandeStack = Stack()
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tokenList = postfixExp.split(" ")
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for (i,token) in enumerate(tokenList):
if token in "+-*/":
op2 = operandeStack.pop()
op1 = operandeStack.pop()
res = doMath(token, op1, op2)
operandeStack.push(res)
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#print("Operation: {op1} {op} {op2}".format(op1 = op1, op = token, op2 = op2))
#print(operandeStack)
#print(tokenList[i+1:])
newPostfix = " ".join(operandeStack + tokenList[i+1:])
print(postfixToInfix(newPostfix))
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else:
operandeStack.push(token)
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return operandeStack.pop()
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def computePostfixBis(postfixExp):
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"""Compute a postfix expression like a good student
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:param postfixExp: a postfix expression
:returns: the result of the expression
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"""
print(postfixToInfix(postfixExp))
# where to save numbers or
operandeStack = Stack()
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tokenList = postfixExp.split(" ")
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# On fait le calcul jusqu'à n'avoir plus qu'un élément
while len(tokenList) > 1:
tmpTokenList = []
# on va chercher les motifs du genre A B + pour les calculer
while len(tokenList) > 2:
if isNumber(tokenList[0]) and isNumber(tokenList[1]) and tokenList[2] in "+-*/":
# S'il y a une opération à faire
op1 = tokenList[0]
op2 = tokenList[1]
token = tokenList[2]
res = doMath(token, op1, op2)
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tmpTokenList.append(res)
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# Comme on vient de faire le calcul, on peut détruire aussi les deux prochains termes
del tokenList[0:3]
else:
tmpTokenList.append(tokenList[0])
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del tokenList[0]
tmpTokenList += tokenList
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tokenList = tmpTokenList.copy()
print(postfixToInfix(" ".join(tokenList)))
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return tokenList[0]
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def isNumber(exp):
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"""Check if the expression can be a number
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:param exp: an expression
:returns: True if the expression can be a number and false otherwise
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"""
tokenList = exp.split(" ")
if len(tokenList) != 1:
# si l'expression est trop longue pour être un chiffre
return 0
return exp.isdigit() or (exp[0] == "-" and exp[1:].isdigit())
def doMath(op, op1, op2):
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"""Compute "op1 op op2"
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:param op: operator
:param op1: first operande
:param op2: second operande
:returns: string representing the result
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"""
return str(eval(op1 + op + op2))
def postfixToInfix(postfixExp):
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"""Transforme postfix expression into infix expression
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:param postfixExp: a postfix expression
:returns: the corresponding infix expression
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"""
operandeStack = Stack()
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tokenList = postfixExp.split(" ")
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for (i,token) in enumerate(tokenList):
if token in "+-*/":
op2 = operandeStack.pop()
if needPar(op2, token, "after"):
op2 = "( " + op2 + " )"
op1 = operandeStack.pop()
if needPar(op1, token, "before"):
op1 = "( " + op1 + " )"
res = "{op1} {op} {op2}".format(op1 = op1, op = token, op2 = op2)
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operandeStack.push(res)
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else:
operandeStack.push(token)
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return operandeStack.pop()
def needPar(operande, operator, posi = "after"):
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"""Says whether or not the operande needs parenthesis
:param operande: the operande
:param operator: the operator
:param posi: "after"(default) if the operande will be after the operator, "before" othewise
:returns: bollean
"""
priority = {"*" : 3, "/": 3, "+": 2, "-":2}
if isNumber(operande) and "-" in operande:
return 1
elif not isNumber(operande):
# Si c'est une grande expression ou un chiffre négatif
stand_alone = get_main_op(operande)
# Si la priorité de l'operande est plus faible que celle de l'opérateur
minor_priority = priority[get_main_op(operande)] < priority[operator]
# Si l'opérateur est -/ pour after ou juste / pour before
special = (operator in "-/" and posi == "after") or (operator in "/" and posi == "before")
return stand_alone and (minor_priority or special)
else:
return 0
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def get_main_op(exp):
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"""Getting the main operation of the expression
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:param exp: the expression
:returns: the main operation (+, -, * or /) or 0 if the expression is only one element
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"""
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priority = {"*" : 3, "/": 3, "+": 2, "-":2}
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parStack = Stack()
tokenList = exp.split(" ")
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if len(tokenList) == 1:
# Si l'expression n'est qu'un élément
return 0
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main_op = []
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for token in tokenList:
if token == "(":
parStack.push(token)
elif token == ")":
parStack.pop()
elif token in "+-*/" and parStack.isEmpty():
main_op.append(token)
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return min(main_op, key = lambda s: priority[s])
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def expand_list(list_list):
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"""Expand list of list
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:param list: the list to expande
:returns: list of expanded lists
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:Example:
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>>> expand_list([1,2,[3,4],5,[6,7,8]])
[[1, 2, 3, 5, 6], [1, 2, 4, 5, 7], [1, 2, 4, 5, 8]]
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"""
list_in_list = [i for i in list_list if type(i) == list].copy()
nbr_ans_list = max([len(i) for i in list_in_list])
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ans = [list_list.copy() for i in range(nbr_ans_list)]
for (i,l) in enumerate(ans):
for (j,e) in enumerate(l):
if type(e) == list:
ans[i][j] = e[min(i,len(e)-1)]
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return ans
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def debug_var(name, var):
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"""print the name of the variable and the value
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:param name: the name of the variable
:param var: the variable we want information
"""
print(name, ": ", var)
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def test(exp):
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"""Make various test on an expression
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"""
print("-------------")
print("Expression ",exp)
postfix = infixToPostfix(exp)
#print("Postfix " , postfix)
#print(computePostfix(postfix))
#print("Bis")
print(computePostfixBis(postfix))
#print(postfixToInfix(postfix))
#print(get_main_op(exp))
if __name__ == '__main__':
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#exp = "1 + 3 * 5"
#test(exp)
#exp = "2 * 3 * 3 * 5"
#test(exp)
#exp = "2 * 3 + 3 * 5"
#test(exp)
#exp = "2 * ( 3 + 4 ) + 3 * 5"
#test(exp)
#
#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)
#
#exp = "( 2 + 5 ) * ( 3 - 4 )"
#test(exp)
#
#exp = "( 2 + 5 ) * ( 3 * 4 )"
#test(exp)
#
#exp = "( 2 + 5 ) / ( 3 * 4 )"
#test(exp)
#print(expand_list([1,2,['a','b','c'], 3, ['d','e']]))
## Ce denier pose un soucis. Pour le faire marcher il faudrai implémenter le calcul avec les fractions
#exp = "( 2 + 5 ) / 3 * 4"
#test(exp)
import doctest
doctest.testmod()
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