Generating Fibonacci series in Python - python-3.x

Question

I want to simple generate the fibonacci series in Python. But somehow i don't see the correct series. For example if i input 3 then the correct answer should come with the series : 1 1 2 3
Below is my code.Can someone please point out what is wrong with this :
def genfibonacci(no):
if no <= 1:
return no
else:
sum = genfibonacci(no - 1) + genfibonacci(no - 2)
print (sum)
return(sum)
number = int(input())
genfibonacci(number)
Thanks in advance.

Answer 1

Part of your problem is printing while you calculate (apart from if no <= 1)
If we remove the print, and just show what you get as a result this will help:
def genfibonacci(no):
if no <= 1:
sum = no
else:
sum = genfibonacci(no-1) + genfibonacci(no-2)
return sum
>>> [genfibonacci(i) for i in range(4)]
[0, 1, 1, 2]
>>> [genfibonacci(i) for i in range(5)]
[0, 1, 1, 2, 3]
This range starts at 0, so you can remove that if you want.
Since genfibonacci for say 4 will call 32 and 2, which in turn will call 2 and 1, the print statement you have will happen for the same number more than once.
And not at all for the no <= 1.

Answer 2

There are so many ways to calculate fibonacci sesries in python..
Example 1: Using looping technique
def fib(n):
a,b = 1,1
for i in range(n-1):
a,b = b,a+b
return a
print fib(5)
Example 2: Using recursion
def fibR(n):
if n==1 or n==2:
return 1
return fib(n-1)+fib(n-2)
print fibR(5)
Example 3: Using generators
a,b = 0,1
def fibI():
global a,b
while True:
a,b = b, a+b
yield a
f=fibI()
f.next()
f.next()
f.next()
f.next()
print f.next()
Example 4: Using memoization
def memoize(fn, arg):
memo = {}
if arg not in memo:
memo[arg] = fn(arg)
return memo[arg]
fib() as written in example 1.
fibm = memoize(fib,5)
print fibm
Example 5: Using memoization as decorator
class Memoize:
def __init__(self, fn):
self.fn = fn
self.memo = {}
def __call__(self, arg):
if arg not in self.memo:
self.memo[arg] = self.fn(arg)
return self.memo[arg]
#Memoize
def fib(n):
a,b = 1,1
for i in range(n-1):
a,b = b,a+b
return a
print fib(5)

Answer 3

Here the Simplest Fibonacci Series represnted:
#Fibonacci series in Short Code
#initilize the base list
ls2=[0,1]
#user input: How many wants to print
c=int(input('Enter required numbers:'))
#fibonacci Function to add last two elements of list
ls2.extend((ls2[i-1]+ls2[i-2]) for i in range(2,c))
#This will print recuired numbers of list
print(ls2[0:c])
If you Want Create Function Then:
#Fibonacci series in Short Code
#initilize the base list
ls2=[0,1]
#user input: How many wants to print
c=int(input('Enter required numbers:'))
#fibonacci Function to add last two elements of list
def fibonacci(c):
ls2.extend((ls2[i-1]+ls2[i-2]) for i in range(2,c))
#This will print required numbers of list
print(ls2[0:c])
fibonacci(c)

Answer 4

Fibonacci using Recursive Function in Python:
def fibonacci(n, fib1=0, fib2=1):
if n<=1:
print(fib1)
return
else:
print(fib1)
fib = fib1 + fib2
fib1 = fib2
fib2 = fib
fibonacci(n - 1, fib1, fib2)
number = int(input())
fibonacci(number)

Answer 5

There are different methods you can use but I use the method of recursion because here you have to code less
def fib(n):
if n<=1:
return n
else:
return fib(n-1)+fib(n-2)
n = int(input())
for i in range(n):
print(fib(i),sep=' ',end=' ')