Python：如何使用字典将运算符的字符串表示形式分配给数学运算符？

Question

My aim is to create a UDF that does simple arithmetic. I want the function to take 2 values, and then a string representation of an operator, for example 'mulitiply' and perform the operator on x to y. This is my first time attempting this, excuse the mess.

def_myArithmetic(x, y, op):
     op={'multiply': *, 'divide': /, 'add': +, 'subtract':-}
     **some loop**
         **return calculation**

what I have managed so far

import operator
def do_arithmetic(x, y, op):
  op={'multiply': operator.multiply,'divide': operator.divide,'add': operator.add ,'subtract': operator.subtract}
  for i in range(x,y):
     print (x, y)

using this bloc of code returns an error when calling the function.

Im aware this dictionary does not work. And i believe its to do with having multiple keys within one reference?

I believe im somewhere near the right lines but clearly have no idea how to write this. It would be very helpful to have something to reference when I try to implement the rules of my choosing.

Thank you for your feedback

Answer 1

Your dictionary variable is replacing the op parameter. Use a different name for this.

You need to use the string argument as a key to access the corresponding dictionary element.

You need to call the operator function, not just put it in a tuple with the arguments.

There's no reason for the for loop.

There's no operator.multiply , it's operator.mul . Find the full list here .

def do_arithmetic(x, y, op):
    operations = {
        'multiply': operator.mul,
        'divide': operator.truediv,
        'add': operator.add,
        'subtract': operator.sub
    }
    return operations[op](x, y)