Python asks for a two-list set difference

I. Two list difference sets

If you have the following two arrays:

A = [1,2,3]

b = [2,3]

The desired result is [1]

Here's a record of three implementations:

1. The normal way

The code is as follows
RET = [] For I in A: If I not in B: Ret.append (i)

2. Condensed version

The code is as follows
RET = [I for i in a if I am not in B]

3. Another edition

The code is as follows
ret = List (set (a) ^ set (b))

Www.111cn.net Webmaster personally prefer a third way of implementation

Two. Get the collection of two list

The code is as follows
Print List (set (a). Union (set (b))

Three. Get the difference set of two list

The code is as follows
Print List (set (b). Difference (set (a))) # B and there's nothing in a