2. Lambda functions

Lambda function

• A lambda function is a small anonymous function. A lambda function can take any number of arguments, but can only have one expression

raise_to_power = lambda x, y: x ** y

raise_to_power(2, 3)

• Anonymous functions
  • Function map takes two arguments: map(func, seq)
  • map() applies the function to ALL elements in the sequence

nums = [48, 6, 9, 21, 1]

square_all = map(lambda num: num ** 2, nums)

print(square_all)

print(list(square_all))

Map() and lambda functions

• Function map takes two arguments

spells = ["protego", "accio", "expecto patronum", "legilimens"]

shout_spells = map(lambda item: item + '!!!', spells) # Use map() to apply a lambda function over spells

shout_spells_list = list(shout_spells) # Convert shout_spells to a list: shout_spells_list=

print(shout_spells_list)

Filter() and lambda functions

• The function filter() offers a way to filter out elements from a list that don't satisfy certain criteria

fellowship = ['frodo', 'samwise', 'merry', 'pippin', 'aragorn', 'boromir', 'legolas', 'gimli', 'gandalf']

result = filter(lambda member: len(member) > 6, fellowship) # Use filter() to apply a lambda function over fellowship

result_list = list(result) # Convert result to a list

print(result_list)

Reduce() and lambda functions

• The reduce() function is useful for performing some computation on a list

from functools import reduce # Import reduce from functools

stark = ['robb', 'sansa', 'arya', 'brandon', 'rickon']

result = reduce(lambda item1, item2: item1 + item2, stark) # Use reduce() to apply a lambda function over stark

print(result)