An algorithm to evaluate mathematical expressions by partial postfix conversion optimization

InfixToPostfix.py

#precedance and the operation of each binary operator
prec = { "**": 3,
         "*": 2,
         "/": 2,
         '%': 2,
         "+": 1,
         "-": 1,
         "$": 0}
operFunc = {'+': lambda a, b: a + b,
            '-': lambda a, b: a - b,
            '*': lambda a, b: a * b,
            '/': lambda a, b: a / b,
            '%': lambda a, b: a % b,
            "**": lambda a, b: a ** b}

#Get the user input
operator, operand = [], []
expr = input() + " $"

for i in expr.split(" "):
    #print(operand, operator, i)
    if i.isdigit():
        #Push all the operands into the stack
        operand.append(int(i))
    else:
        #While the precedance of the top of stack
        #is equal to or less than new operator
        #perform the opration of operator on top of the stack
        #and then push the new operator
        while len(operator) > 0 and prec[i] <= prec[operator[len(operator) - 1]]:
            #print(operand, operator)
            opr = operator.pop()
            op1 = operand.pop()
            op2 = operand.pop()
            operand.append(func[opr](op2, op1))
        operator.append(i)
print(operand[0])

A simple python program to evaluate an infix expression by converting it to a post fix expression