Lambda Code Logic

Question

Could anyone let me know what lower() do here?

Also how this code sorted the list?

https://code.sololearn.com/cyGB02ZHLAFT/?ref=app

Answer 1

Assume that list have names like ' firstName secondName' so it splitting this name to 2 parts by space then converting last(secondName) one to lower case and this is a key now to sort items..

'Alf Zed' , 'Mike Mo' , 'Steve Aardvark'
This result to by lambda is
'zeb, mo, aradvark' this gets sorted to 'aradvark, mo, zed'.. now it's corresponding original values gets this order..

Answer 2

Also... the line below is a bit unnecessary:

names.sort(key=lambda x: x.split()[-1].lower())

It could be simplified as:
names.sort(key=lambda x: x.split()[1])

The .lower() method isn't necessary here and neither is the reverse index.