#The Fibonacci sequence is a number sequence where each #number is the sum of the previous two numbers. The first #two numbers a
re defined as 0 and 1, so the third number is #1 (0 + 1 = 1), the fourth number is 2 (1 + 1 = 2), the #fifth number is 3 (1 + 2 = 3), the sixth number is 5 #(2 + 3 = 5), and so on.
#
#Below we've started a class called FibSeq. At any time, #FibSeq holds two values from the Fibonacci sequence: #back1 and back2.
#
#Create a new method inside FibSeq called next_number. The #next_number method should:
#
# - Calculate and return the next number in the sequence, # based on the previous 2. # - Update back2 with the former value of back1, and update # back1 with the new next item in the sequence.
#
#This means that consecutive calls to next_number should #yield each consecutive number from the Fibonacci sequence. #Calling next_number 5 times would print 1, 2, 3, 5, and 8.
class FibSeq:
def __init__(self):
self.back1 = 1
self.back2 = 0
def next_number(self):
self.back1=self.back1+self.back2 # updated the back1 value to the next number in the series first
self.back2=self.back1-self.back2 #updated the back2 value with previous back1 value
yield (self.back1) # yielded the next number in the series since it is updated as back1 so yielded back1
f = FibSeq()
for i in range(5): # here i have iterated the series only 5 times u can change it as you like
s=f.next_number()
print(next(s))# here next is an iterator function for the yield generator.
#The code below will test your method. It's not used for
#grading, so feel free to change it. As written, it should
#print 1, 2, 3, 5, and 8.
newFib = FibSeq()
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
#
#Below we've started a class called FibSeq. At any time, #FibSeq holds two values from the Fibonacci sequence: #back1 and back2.
#
#Create a new method inside FibSeq called next_number. The #next_number method should:
#
# - Calculate and return the next number in the sequence, # based on the previous 2. # - Update back2 with the former value of back1, and update # back1 with the new next item in the sequence.
#
#This means that consecutive calls to next_number should #yield each consecutive number from the Fibonacci sequence. #Calling next_number 5 times would print 1, 2, 3, 5, and 8.
class FibSeq:
def __init__(self):
self.back1 = 1
self.back2 = 0
def next_number(self):
self.back1=self.back1+self.back2 # updated the back1 value to the next number in the series first
self.back2=self.back1-self.back2 #updated the back2 value with previous back1 value
yield (self.back1) # yielded the next number in the series since it is updated as back1 so yielded back1
f = FibSeq()
for i in range(5): # here i have iterated the series only 5 times u can change it as you like
s=f.next_number()
print(next(s))# here next is an iterator function for the yield generator.
#The code below will test your method. It's not used for
#grading, so feel free to change it. As written, it should
#print 1, 2, 3, 5, and 8.
newFib = FibSeq()
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
print(newFib.next_number())
1 answer:
Answer:
Here is the next_number method:
def next_number(self): #method to return next number in the sequence
temporary = self.back1 + self.back2 # adds previous number to next number and stores the result in a temporary variable
self.back2 = self.back1 #Updates back2 with the former value of back1,
self.back1 = temporary #update back1 with the new next item in the sequence.
return temporary #
Explanation:
I will explain the working of the above method.
back1 = 1
back2 = 0
At first call to next_number() method:
temporary = back1 + back2
= 1 + 0
temporary = 1
self.back2 = self.back1
self.back2 = 1
self.back1 = temporary
self.back1 = 1
return temporary
This return statement returns the value stored in temporary variable i.e. 1
Output: 1
back1 = 1
back2 = 1
At second call to next_number() method:
temporary = back1 + back2
= 1 + 1
temporary = 2
self.back2 = self.back1
self.back2 = 1
self.back1 = temporary
self.back1 = 2
return temporary
This return statement returns the value stored in temporary variable i.e. 2
output: 2
back1 = 2
back2 = 1
At second call to next_number() method:
temporary = back1 + back2
= 2 + 1
temporary = 3
self.back2 = self.back1
self.back2 = 2
self.back1 = temporary
self.back1 = 3
return temporary
This return statement returns the value stored in temporary variable i.e. 3
Output: 3
back1 = 3
back2 = 2
At second call to next_number() method:
temporary = back1 + back2
= 3 + 2
temporary = 5
self.back2 = self.back1
self.back2 = 3
self.back1 = temporary
self.back1 = 5
return temporary
This return statement returns the value stored in temporary variable i.e. 5
Output: 5
back1 = 5
back2 = 3
At second call to next_number() method:
temporary = back1 + back2
= 5 + 3
temporary = 8
self.back2 = self.back1
self.back2 = 5
self.back1 = temporary
self.back1 = 8
return temporary
This return statement returns the value stored in temporary variable i.e. 8
Output: 8
Calling next_number 5 times would print 1, 2, 3, 5, and 8.
The complete program along with its output is attached.
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