Where to use Map and Filter i am confused :-

Question

L = [i for i in range(0,11)]

x = map(lambda a : True if (a%2 == 0) else False, L)
new = []
#output = [True, False, True, False, True, False, True, False, True, False, True]

for i in x:
new.append(i)
print(new)

#and

x = filter(lambda a : True if (a%2 == 0) else False, L)

new = []
#output = [0,2,4,6,8,10]
for i in x:
new.append(i)
print(new)

https://code.sololearn.com/cy91Ks86A9A3/?ref=app

Answer 1

You gave two examples of how to use them yourself.

Can you explain what you really want to know?

You use map when you want to use a function or method on every element of an iterable.

print(*map(float, [1, 2, 3, 4, 5]))

Output: 1.0 2.0 3.0 4.0 5.0

Every number gets turned into a float.

You use filter when you only want to keep elements of an iterable that fulfill a condition, determined by a function returning True or False.

print(*filter(str.isdigit, 'solo123learn456'))

Output: 123456

(The * just 'unpacks' the map or filter object for printing the elements.)

Answer 2

I have edited my post, please read it.

Does that clarify it a bit?

Answer 3

Simply map convertes all element in a list to another value after doing some functional expressions.
In your example it maps all of the integers in the list (list for generated with a sequence from 0 to 10 using range method) to the boolean value True if they are divisible by 2. otherwise it will map those indivisible value to False.

And in the second example it filters - or it returns all the elements in the list which match the given condition.
In this case all the values divisible by 2 are filtered out from the function.
Filter method is just like a filter that you use in your day to day life

Answer 4

HonFu I know working but confused where to use them.

Answer 5

HonFu please tell me

Answer 6

Why

https://code.sololearn.com/cvGVy6IpT4HD/?ref=app