Lambda functions¶
In Python, a lambda function is an anonymous function, that is, a function that is declared without a name. It is a small and restricted function that is no longer than one line. Like a normal function, a lambda function can have several arguments, but only one expression that is evaluated and returned.
The syntax of a lambda function is
lambda ARGUMENTS: EXPRESSION
>>> add = lambda x, y: x + y
>>> add(2, 3)
5
Note
There is no return statement in the lambda function. The single
expression after the colon is the return value.
In the next example, a lambda function is created within a function call. However, there is no global variable to store the values of the lambda function:
1>>> count = ["1", "123", "1000"]
2>>> max(count)
3'123'
4>>> max(count, key=lambda val: int(val))
5'1000'
In this case, the max() function accepts the key argument, which
defines how the size of each entry is to be determined. Using a lambda function
that converts each string into an integer, max can compare the numerical
values to determine the expected result.