Partial functions allow us to fix a certain number of arguments of a function and generate a new function.
Example:
from functools import partial
# A normal function
def f(a, b, c, x):
return 1000*a + 100*b + 10*c + x
# A partial function that calls f with
# a as 3, b as 1 and c as 4.
g = partial(f, 3, 1, 4)
# Calling g()
print(g(5))
Output:
3145
In the example we have pre-filled our function with some constant values of a, b and c. And g() just takes a single argument i.e. the variable x.
Another Example :
from functools import *
# A normal function
def add(a, b, c):
return 100 * a + 10 * b + c
# A partial function with b = 1 and c = 2
add_part = partial(add, c = 2, b = 1)
# Calling partial function
print(add_part(3))
Output:
312
Partial functions can be used to derive specialized functions from general functions and therefore help us to reuse our code.
This feature is similar to bind in C++.