These are three functions which facilitate a functional approach to
programming. We will discuss them one by one and understand their use
cases.
Map applies a function to all the items in an input_list. Here is
the blueprint:
Blueprint
map
(
function_to_apply
,
list_of_inputs
)
Most of the times we want to pass all the list elements to a function
one-by-one and then collect the output. For instance:
items
=
[
1
,
2
,
3
,
4
,
5
]
squared
=
[]
for
i
in
items
:
squared
.
append
(
i
**
2
)
Map allows us to implement this in a much simpler and nicer way.
Here you go:
items
=
[
1
,
2
,
3
,
4
,
5
]
squared
=
list
(
map
(
lambda
x
:
x
**
2
,
items
))
Most of the times we use lambdas with map so I did the same. Instead
of a list of inputs we can even have a list of functions!
def
multiply
(
x
):
return
(
x
*
x
)
def
add
(
x
):
return
(
x
+
x
)
funcs
=
[
multiply
,
add
]
for
i
in
range
(
5
):
value
=
list
(
map
(
lambda
x
:
x
(
i
),
funcs
))
(
value
)
# Output:
# [0, 0]
# [1, 2]
# [4, 4]
# [9, 6]
# [16, 8]
