Why work It?

Question

I have this code, and work only if I use any(), and I don't know why this don't work without any()

a=[0,1]
b=[0,1]

map(lambda _: a.append(sum(a[-2:])),range(2,10))

any(map(lambda _: b.append(sum(b[-2:])),range(2,10)))

print(a)
print(b)

Answer 1

# Hi, Pedro Dominguez !

# In your code,

# map(lambda _: a.append(sum(a[-2:])),range(2,10))

# creates an iterator. When you put any() around it, it will result in that you traverse through the iterator, calling the lambda function each time it iterate.

# So map() will just act as a loop and run the lambda function:

# lambda _: a.append(sum(a[-2:])

# which create a Fibonacci sequence when the the function is looped. A better approach would be this:

def f(n):
l = [0, 1]
for i in range(2, n):
l.append(sum(l[-2:]))
return l[:]

print(f"{f(10) = }\n")

# You can get the same with your map function, but it is not a good approach:

a = [0,1]

m = map(lambda _: a.append(sum(a[-2:])),range(2,10))

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

next(m)
print(a)

# and your list a will slowly growe...

https://code.sololearn.com/cIG5i23pqfm3/?ref=app