Lambda Functions

The lambda expression allows you to define a function without the def statement:

names = ['Ada', 'Bob', 'Charlotte', 'Dave', 'Eddy']

# find words with an odd/even number of characters
odd = lambda s:len(s) % 2
even = lambda s:not odd(s)

print('odd :', [x for x in names if odd(x)])
print('even:', [x for x in names if even(x)])

The advantage of lambda is that it can be combined with other functional expressions like map(), filter() and reduce():

odd_names = list(filter(lambda s:len(s) % 2, names))

Excessive use of lambda does not necessarily make your code more clean. But if you would like to experiment with functional programming it is worth to know.

Dr. Kristian Rother

I am a professional Python trainer, developer and author based in Berlin. I believe everybody can learn programming.

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You successfully explained a complicated software in the easiest way possible. Very good approach! After five short days I feel I have learned a lot and can continue! Thank you!

Nasrin H, Freie Universität Berlin

See also