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Python | Find fibonacci series upto n using lambda
  • Difficulty Level : Expert
  • Last Updated : 17 Mar, 2019

The Fibonacci numbers are the numbers in the following integer sequence.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ……..

In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relation

Fn = Fn-1 + Fn-2  with seed values   F0 = 0 and F1 = 1.



Find the series of fibonacci numbers using lambda function.

Code #1 : By using lambda and reduce method




from functools import reduce
  
fib = lambda n: reduce(lambda x, _: x+[x[-1]+x[-2]],
                                 range(n-2), [0, 1])
  
print(fib(5))
Output:
[0, 1, 1, 2, 3]

Explanation :

The list taking first two parameters is 0 and 1, and add like x[-1] i.e 0 and x[-2] i.e 1 and append to variable x. There is a type conversion to list and due to reduce() method, the same function calls and due to range function this time parameter changes, then add this to previous result and again store it to list.
 

Code #2 : By using lambda and map function




def fibonacci(count):
    fib_list = [0, 1]
  
    any(map(lambda _: fib_list.append(sum(fib_list[-2:])),
                                         range(2, count)))
  
    return fib_list[:count]
  
print(fibonacci(10))
Output:
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

Explanation :
We are taking the list fib_list which already has 0 and 1. Then in the next iteration, this will be used as input and result of their sum will append to the list.

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