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June 13, 2020 08:41 pm GMT
Original Link: https://dev.to/adamlombard/python-what-is-a-lambda-function-3m98
Python: What is a Lambda Function?
In Python, the lambda
keyword is used to define an anonymous (i.e., nameless) function, using the following syntax:
lambda parameters: expression
Assume we have the following list of fruits:
fruits = ['apple', 'orange', 'grape', 'lemon', 'mango', 'banana']
Now imagine we need to filter our list to print only fruit names which are 5 characters long. We could do so by defining a named function to test word lengths, and then passing it (and our list of fruits) to filter()
:
def five_letter_words(word): if len(word) == 5: return Truefive_letter_fruits = filter(five_letter_words, fruits)for fruit in five_letter_fruits: print(fruit)
applegrapelemonmango>>>
Or, the same task can be accomplished directly in filter()
using a lambda
expression, without needing to define a separate named function:
five_letter_fruits = filter(lambda word: len(word) == 5, fruits)for fruit in five_letter_fruits: print(fruit)
applegrapelemonmango>>>
Because lambda functions are Python expressions, they can be assigned to variables.
So, this:
add_two = lambda x, y: x+yadd_two(3, 5)
Is equivalent to this:
def add_two(x, y): return x + yadd_two(3, 5)
Original Link: https://dev.to/adamlombard/python-what-is-a-lambda-function-3m98
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