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