Implementing recursion in Python

Question

I am currently working on recursion in Python but even though my process is correct I do not get my output format as I wanted.

def fibonacci(n):
if n <= 2:
    return 1
else:
    return fibonacci(n-1) + fibonacci(n-2)

def fibseries(N):
    if N <= 1:
        return []
    return [fibseries(N-1),fibonacci(N-1)]
a = fibseries(5)
print a

This gives me the output :

[[[[[0], 1], 1], 2], 3]

but I want to get:

[0, 1, 1, 2, 3]

I need to understand the thinking process.

have you seen stackoverflow.com/questions/494594/… possible duplicate — Dan-Dev
– Dan-Dev, Commented Dec 17, 2016 at 21:03
It looks like you are returning an array each tim, hence the nesting — Mikkel
– Mikkel, Commented Dec 17, 2016 at 22:35

Anthon · Accepted Answer · 2016-12-17 21:23:48Z

1

The problem is that fibseries returns a list and within fibseries you do:

return [fibseries(N-1),fibonacci(N-1)]

you should concatenate the fibonacci output:

return fibseries(N-1) + [fibonacci(N-1)]

answered Dec 17, 2016 at 21:23

Anthon

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1 Comment

Dante Over a year ago

Thank you very much now I understand my mistake and I can get my result in the given format!

m3wolf · Accepted Answer · 2016-12-17 21:23:57Z

0

The problem is in the line return [fibseries(N-1),fibonacci(N-1)]. Each time you call fibseries, it returns a list so this line creates a new list with two elements, the first of which is itself a list. To get it to do what you want replace that line with return [*fibseries(N-1),fibonacci(N-1)]. The star will expand the first list and add the elements separately.c

answered Dec 17, 2016 at 21:23

m3wolf

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