How to write the Fibonacci Sequence

Question

I had originally coded the program wrongly. Instead of returning the Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 should = only those numbers between 1 & 20), I have written for the program to display all Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 displays = First 20 Fibonacci numbers). I thought I had a sure-fire code. I also do not see why this is happening.

startNumber = int(raw_input("Enter the start number here "))
endNumber = int(raw_input("Enter the end number here "))
def fib(n):
    if n < 2:
        return n
        return fib(n-2) + fib(n-1)
print map(fib, range(startNumber, endNumber))

Can someone please point me in the direction on how to do this? Any help is welcome.

I'm a learning programmer and I've run into a bit of a jumble. I am asked to write a program that will compute and display Fibonacci's Sequence by a user inputted start number and end number (ie. startNumber = 20 endNumber = 100 and it will display only the numbers between that range). The trick is to use it inclusively (which I do not know how to do in Python? - I'm assuming this means to use an inclusive range?).

What I have so far is no actual coding but rather:

• Write Fib sequence formula to infinite

• Display startNumber to endNumber only from Fib sequence.

I have no idea where to start and I am asking for ideas or insight into how to write this. I also have tried to write the Fib sequence forumla but I get lost on that as well.

Answer 1

Efficient Pythonic generator of the Fibonacci sequence

I found this question while trying to get the shortest Pythonic generation of this sequence and I haven't noticed anyone else coming up with my specific solution (although the top answer gets close, but still less elegant), so here it is, with comments describing the first iteration, because I think that may help readers understand:

def fib():
    a, b = 0, 1
    while True:
    # First iteration:
        yield a
        # yield 0 to start with and then
        a, b = b, a + b # a will now be 1, and b will also be 1, (0 + 1)

and usage:

for index, fibonacci_number in zip(range(10), fib()):
    print('{i:3}:
        {f:3}'.format(i=index, f=fibonacci_number))

prints:

0: 0
1: 1
2: 1
3: 2
4: 3
5: 5
6: 8
7: 13
8: 21
9: 34
10: 55