Question

Given the code:

a=['a','b','c','d']
b=a[::-1]
print b
c=zip(a,b)
print c
c.sort(key=lambda x:x[1])#
print c

It prints:

['d', 'c', 'b', 'a']
[('a', 'd'), ('b', 'c'), ('c', 'b'), ('d', 'a')]
[('d', 'a'), ('c', 'b'), ('b', 'c'), ('a', 'd')]

Why does [(‘a’, ‘d’), (‘b’, ‘c’), (‘c’, ‘b’), (‘d’, ‘a’)] change to [(‘d’, ‘a’), (‘c’, ‘b’), (‘b’, ‘c’), (‘a’, ‘d’)]?

---

Similarly, given:

c.sort(key=lambda x:3)#
print c

It prints:

[('a', 'd'), ('b', 'c'), ('c', 'b'), ('d', 'a')]

Nothing changes – why?

Answer 1

because x[1] means second

use

c.sort(key=lambda x:x[0])