Python - scope and recursive function - Day 25(4 days later)

this will explain the variable's scope.

  
#take way:read the document related to local,nonlocal,global
#know what is LEGB - Local Enclosing Global Builtins
#below example will illustrate the variable and the scope of it


# def spam1():
#     def spam2():
#         def spam3():
#             z = ' even more spam'
#             print('3 {}'.format(locals()))
#             return z
#         y = 'more spam '
#         y+= spam3()
#         print('2 {}'.format(locals()))
#         return y
#     x = 'spam '
#     x+= spam2()
#     print('1 {}'.format(locals()))
#     print(x)

def spam1():
    def spam2():
        def spam3():
            # y = 'test'
            z = ' even' + y
            print('3 {}'.format(locals()))
            return z
        y = ' more'+x
        y+= spam3()
        print('2 {}'.format(locals()))
        return y
    x = 'spam'
    x+= spam2()
    # we can't write like this x = 'spam' + spam2(),since spam2 function first expects x
    # it will throw unreferenced variable error if we code like that
    print('1 {}'.format(locals()))
    print(x)

print(spam1())
print(locals())
print(globals())
 

this will explain how the recursive funtion can be made use of

  
#recursive function,function that calls itself again and again
#factorial

def factorial(n):
    result = 1
    if n>1:
        for i in range (1,n+1):
            result = result * i
    return result

def factorialrec(n):
    #n factorial can also be defined as n * (n-1)!
    if n<=1:
        return 1
    else:
        return n * factorialrec(n-1)

def fibonaccirec(n):
    # Fn = Fn-1 + Fn-2
    if n<2:
        return n
    else:
        return fibonaccirec(n-1)+fibonaccirec(n-2)

def fibonacci(n):
    if n == 0:
        return 0
    if n == 1:
        return 1
    elif n==2:
        return 1
    else:
        n_minus1 = 1
        n_minus2 = 0
        for i in range(1,n):
            result = n_minus1+n_minus2
            n_minus2 = n_minus1
            n_minus1 = result
        return result




# for x in range (1,130):
#     print(x , factorial(x))

# for x in range (1,130):
#     print(x , factorialrec(x))

# here use of the recursive funtion in calculating the fibonaaci
#might slow downb the process,so we can go for direct method

# for x in range (1,36):
#     print(x , fibonaccirec(x))

#below direct method will be fast
for x in range (1,36):
    print(x , fibonacci(x))