从列表中删除而不影响虚拟变量

Question

 from random import choice

inputs=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','1','2','3','4','5','6','7','8','9','0']
func={}
code=""
z=len(inputs)
x=z-1
temp=inputs
while x>=0:
    y=choice(temp)
    print(str(x)+"   "+inputs[x]+"   "+y)
    func[inputs[x]]=y
    code=code+inputs[x]+y
    del temp[x]
    x=x-1
    print(temp)
    print(inputs)

Why does this code not asign every element of inputs to a unique and random element of inputs(as the temp dummy set)? it seems to delete items from both temp and inputs when only told to delete items from the dummy set.

Thanks for any help.

Answer 1

You are creating an alias of your list instead of a true copy of it: replace temp=inputs with temp=inputs[:]

import random

inputs =  ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','1','2','3','4','5','6','7','8','9','0']
func = {}
code = ""
z = len(inputs)
x = z-1
temp = inputs[:]    #<-- here
while x >= 0:
    y = random.choice(temp)
    print(str(x) + "   " + inputs[x] + "   " + y)
    func[inputs[x]] = y
    code = code+inputs[x] + y
    del temp[x]
    x = x - 1
    print(temp)
    print(inputs)

Answer 2

You are not making a copy of 'inputs' when you do 'temp=inputs', but making a new variable to access the same content. If you want a new copy of the list, then use 'temp = inputs[:]'. Otherwise you are just creating a new reference to the same object, but not duplicating the object itself.

You can find more about this in the official Python FAQ .