How say to python that (a+b) = (b+a) and (a*b) = (b*a)

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I have all possible combinations of operations between numbers in a list:

list = ['2','7','8']

7+8*2
8+7*2
2*8+7
2+8*7
2-8*7
8-2/7
etc

I want to know if it's possible to say that operations like ('7*2+8' and '8+7*2' and '2*7+8') or (7*8*2 and 2*8*7 and 7*2*8) etc. are the same. I want to know how take only one operation if it's the same operation.

This is my code to create these different operations:

Op = ['+','-','*','/']
array = []
for i in Op:
    array.append(string1 + i + string2)
    return array
list python operators
1 Answers

if I understand you well, I think I have an idea for you.

First of all, you need to create all of the possible permutations of digits and expressions. You can do that in this way:

import itertools
num_list = ['2','7','8']
op = ['+','-','*','/'] * 2 # *2 for the case of same operator twice

num_perm = list(itertools.permutations(num_list))
op_perm = list(itertools.permutations(op, 2)) # We want perm of two operators.

Now, you need to merge all the permutation to a math expression, this is a nice way for that:

list_of_experssions = list()
for num in num_perm :
    for op in op_perm:
        list_of_experssions.append(num[0] + op[0] + num[1] + op[1] +num[2])

The last step is to check if the results of the two expressions are equal (using eval function) but the expressions themself are different:

for exp1 in list_of_experssions:
    for exp2 in list_of_experssions:
        if eval(exp1) == eval(exp2) and exp1 != exp2:
            print(exp1, exp2)

In your case, we got 336 math expressions and 2560 couples of equal expressions.

user_110792840
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