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eval_stack.py
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eval_stack.py
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
import copy
import re
def add_expression(left_expression, right_expression):
left_numerator = left_expression[0]
left_denominator = left_expression[1]
right_numerator = right_expression[0]
right_denominator = right_expression[1]
if len(left_denominator) == 0 and len(right_denominator) == 0:
new_numerator = left_numerator + right_numerator
return [new_numerator, []]
new_numerator_p1 = mul_expression([left_numerator, []],
[right_denominator, []])
new_numerator_p2 = mul_expression([left_denominator, []],
[right_numerator, []])
new_numerator = add_expression(new_numerator_p1, new_numerator_p2)
new_numerator = new_numerator[0]
new_denominator = mul_expression([left_denominator, []],
[right_denominator, []])
new_denominator = new_denominator[0]
return [new_numerator, new_denominator]
def mul_expression(left_expression, right_expression):
left_numerator = left_expression[0]
left_denominator = left_expression[1]
right_numerator = right_expression[0]
right_denominator = right_expression[1]
new_numerator = []
if len(left_numerator) != 0 and len(right_numerator) != 0:
for l in left_numerator:
for r in right_numerator:
new_numerator.append(l + "*" + r)
elif len(left_numerator) == 0:
new_numerator = copy.copy(right_numerator)
elif len(right_numerator) == 0:
new_numerator = copy.copy(left_numerator)
else:
pass
new_denominator = []
if len(left_denominator) != 0 and len(right_denominator) != 0:
for l in left_denominator:
for r in right_denominator:
new_denominator.append(l + "*" + r)
elif len(left_denominator) == 0:
new_denominator = copy.copy(right_denominator)
elif len(right_denominator) == 0:
new_denominator = copy.copy(left_denominator)
else:
pass
return [new_numerator, new_denominator]
def sub_expression(left_expression, right_expression):
right_numerator = right_expression[0]
new_right_numerator = ['(-1)*' + rn for rn in right_numerator]
return add_expression(left_expression,
[new_right_numerator, right_expression[1]])
def div_expression(left_expression, right_expression):
return mul_expression(left_expression,
[right_expression[1], right_expression[0]])
def precedence(op):
if op == '+' or op == '-':
return 1
if op == '*' or op == '/':
return 2
return 0
def multinomial_expand(v1, v2, op):
if isinstance(v1, str):
v1 = [[v1], []]
if isinstance(v2, str):
v2 = [[v2], []]
# print("----------------------------------------------------------")
# print(v1)
# print(v2)
# print(op)
# print("----------------------------------------------------------")
if op == '+':
return add_expression(v1, v2)
elif op == '*':
return mul_expression(v1, v2)
elif op == '-':
return sub_expression(v1, v2)
else:
return div_expression(v1, v2)
def arthmetic_evalue(v1, v2, op):
if op == '+':
return v1 + v2
elif op == '*':
return v1 * v2
elif op == '-':
return v1 - v2
else:
return v1 / v2
def is_number(num_str):
try:
float(num_str)
except:
return False
else:
return True
def evaluate_arithmetic_expression(expression, evaluate_number, precedence,
evaluate_op):
value_stack = []
op_stack = []
tokens = re.split(r'([^0-9\s\.])', expression)
for token in tokens:
if token == '' or token.strip() == '':
continue
elif is_number(token):
value_stack.append(evaluate_number(token))
elif token == "(":
op_stack.append(token)
elif token == ")":
while len(op_stack) != 0 and op_stack[-1] != "(":
op = op_stack.pop()
v2, v1 = value_stack.pop(), value_stack.pop()
value_stack.append(evaluate_op(v1, v2, op))
op_stack.pop()
else:
while len(op_stack) != 0 and precedence(
op_stack[-1]) >= precedence(token):
v2, v1 = value_stack.pop(), value_stack.pop()
op = op_stack.pop()
value_stack.append(evaluate_op(v1, v2, op))
op_stack.append(token)
while len(op_stack) != 0:
v2, v1 = value_stack.pop(), value_stack.pop()
op = op_stack.pop()
value_stack.append(evaluate_op(v1, v2, op))
return value_stack[-1]
def sort_basic_element(elem):
tokens = elem.split("*")
# normalize -1 in mul
no_minus1_tokens = [x for x in tokens if x != '(-1)']
minus1_cnt = len(tokens) - len(no_minus1_tokens)
if minus1_cnt % 2 == 1:
no_minus1_tokens.append('(-1)')
tokens = sorted(no_minus1_tokens, key=lambda x: -eval(x))
return "*".join(tokens)
def signature(expression):
expansion = evaluate_arithmetic_expression(expression, lambda x: x.strip(),
precedence, multinomial_expand)
numerator_expansion = [sort_basic_element(x) for x in expansion[0]]
numerator_expansion = sorted(
numerator_expansion,
key=lambda x: str(len(x.split("*"))) + str(eval(x)))
numerator_expansion = "|".join(numerator_expansion)
denominator_expansion = [sort_basic_element(x) for x in expansion[1]]
denominator_expansion = sorted(
denominator_expansion,
key=lambda x: str(len(x.split("*"))) + str(eval(x)))
denominator_expansion = "|".join(denominator_expansion)
return numerator_expansion + "/" + denominator_expansion
def test_multinomial_expand():
left_expr = [['3*5', '3*2*4', '(-1)*7*10'], ['2', '2*2']]
right_expr = [['2*4', '3', '4*(-1)'], ['10', '5*5', '5']]
print(add_expression(left_expr, right_expr))
print(mul_expression(left_expr, right_expr))
print(sub_expression(left_expr, right_expr))
print(div_expression(left_expr, right_expr))
expression = '(((((((5*(10*((7*2)-1)))-5)*11- 5)*2)/2)*3) - 5)'
expansion = evaluate_arithmetic_expression(expression, lambda x: x.strip(),
precedence, multinomial_expand)
print(expansion)
print(signature(expression))
equi_expr_a = '(((10*5)*((7*2)-(1)))-(5))'
equi_expr_b = '(((5)*((10)*((7*2)-(1))))-(5))'
diff_expr_c = '((2+1)*((5)*((10*5)-(7))))'
diff_expr_d = '((10*7 - 5) *2 - 1) * 5'
print(signature(equi_expr_a))
print(signature(equi_expr_b))
print(signature(diff_expr_c))
print(signature(diff_expr_d))
if __name__ == '__main__':
# test_multinomial_expand()
print(signature('7*(5+2*2)'))
print(signature('7*(5+2+2)'))