pythonsortingtupleskey

How to sort a list with two keys but one in reverse order?

I was wondering what would be a Pythonic way of sorting a list of tuples by two keys whereby sorting with one (and only one) key would be in a reverse order and sorting with the the other would be case insensitive. More specifically, I have a list containing tuples like:

myList = [(ele1A, ele2A),(ele1B, ele2B),(ele1C, ele2C)]

I can use the following code to sort it with two keys:

sortedList = sorted(myList, key = lambda y: (y[0].lower(), y[1]))

To sort in reverse order I can use

sortedList = sorted(myList, key = lambda y: (y[0].lower(), y[1]), reverse = True)

But this would sort in a reverse order with two keys.

Solution

  • Two keys will be used when we need to sort a list with two constraints: one in ascending order and the other in descending, in the same list or any

    In your example,

    sortedList = sorted(myList, key = lambda y: (y[0].lower(), y[1]))

    you can sort entire list only in one order.

    You can try these and check what's happening:

    sortedList = sorted(myList, key = lambda y: (y[0].lower(), -y[1]))
sortedList = sorted(myList, key = lambda y: (-y[0].lower(), y[1]))
sortedList = sorted(myList, key = lambda y: (-y[0].lower(), -y[1]))