fibonnaci Series code in python - python-2.7

Question

I wrote this code in python 2.7 to find Fibonnaci series. But there is error in my code:
File "Fib.py", line 2, in <module>
class Fib:
File "Fib.py", line 21, in Fib
for n in Fib(4):
NameError: name 'Fib' is not defined
Can anyone resolve this bug?
class Fib:
def __init__(self,max):
self.max = max
def __iter__(self):
self.a=0
self.b = 1
return self
def __next__(self) :
fib = self.a
if fib > self.max :
raise StopIteration
a,b=b,self.a+self.b
return fib
for n in Fib(4):
print n

Answer 1

Disclaimer: I cannot reproduce your error from the code you posted (see below for my guess work). However, I still get errors, so I'll fix them.
From your posted code:
I get:
Traceback (most recent call last):
File "a.py", line 17, in <module>
for n in Fib(4):
TypeError: instance has no next() method
It seems, if your targeting python 2.7, that you got mixed up with python 3. The __next__ method was introduced in python 3 (in PEP 3114, if your interested). In python 2, use next. Also, as self must be used to access instance member variables, a,b=b,self.a+self.b should be self.a, self.b = self.b, self.a + self.b. This makes your code:
class Fib:
def __init__(self, max):
self.max = max
def __iter__(self):
self.a = 0
self.b = 1
return self
def next(self):
fib = self.a
if fib > self.max :
raise StopIteration
self.a, self.b = self.b, self.a + self.b
return fib
for n in Fib(4):
print n
Which produces the output:
0
1
1
2
3
Note that changing the next to __next__ and changing print n to print(n) makes this work in python 3 (but then not python 2. If you want both you need to forward next to __next__ and use brackets for print).
Guessed actual code:
Judging from your error, your original code probably looked like:
class Fib:
def __init__(self,max):
self.max = max
def __iter__(self):
self.a=0
self.b = 1
return self
def __next__(self) :
fib = self.a
if fib > self.max :
raise StopIteration
a,b=b,self.a+self.b
return fib
for n in Fib(4): # Note that this makes the loop part of the class body
print n
Indenting the for loop makes it part of the class body, and as the class name is a name not yet accessible, it raises a NameError. For a simpler example, try (it gives a similar error):
class A:
print A
Therefore, the error you experience is most likely just an indentation mixup. Nice idea using an iterator, though.

Answer 2

Easier method to implemented fibonacci series:
known = {0:0, 1:1}
def fibonacci(n) :
if n in known:
return known[n]
res = fibonacci(n-1) + fibonacci(n-2)
known[n] = res
return res

Answer 3

Fibonnaci Series with recursion
def fib(term_num):
if term_num == 0 or term_num ==1:
return term_num
return fib(term_num-2) + fib(term_num-1)
for x in range(1,11):
print(fib(x))
Output Below:
1
1
2
3
5
8
13
21
34
55