Previous lesson: Functions in Python A lambda function is a small, anonymous function. It can take any number of arguments, but at the same time have only one expression.
Syntax
lambda arguments : expression After executing the expression – the result is returned. Lambda functions can take any number of arguments. lambda multiplies the argument a by the argument b and outputs the result:
x = lambda a, b: a * b
print(x(5, 6))
Output:
30
And this function sums the arguments a, b, and c and outputs the result:
x = lambda a, b, c: a + b + c
print(x(5, 6, 2))
Output:
13
Why use lambda functions?
The power of a lambda is better seen when you use it as an anonymous function within another function. Say you have a function definition that takes one argument, and that argument will be multiplied by an unknown number:
def myfunc(n):
return lambda a: a * n
Use this function definition to create a function that always doubles the number you send:
def myfunc(n):
return lambda a: a * n
mydoubler = myfunc(2)
print(mydoubler(11))
Output:
22
Or use the same function definition to make a function that always triples a number:
def myfunc(n):
return lambda a: a * n
mytripler = myfunc(3)
print(mytripler(11))
Conclusion:
33
Or, use the same definition to make both functions in the same program:
def myfunc(n):
return lambda a: a * n
mydoubler = myfunc(2)
mytripler = myfunc(3)
print(mydoubler(11))
print(mytripler(11))
Output:
22
33
Use the lambda function when an anonymous function is needed in a certain part of the code, but not throughout the script.
