Why is it not giving out correct total of first even fibonacci numbers upto 4 mn?
x = 1
y = 2
list = [1,2]
while y< 4000000:
z= x+y
x=y
y=z
list.append (y)
list_even = []
for a in list:
if a%2 == 0:
list_even.append (a)
else:
pass
total = sum(list_even)
print (total)
There are other answers already addressing specific bugs in your code, so I want to offer a completely different implementation that achieves your stated goal:
giving out correct total of first even fibonacci numbers upto 4 mn
If you want to find the sum of the even Fibonacci numbers up to some limit, the code below might be a more functional way of achieving it. It's based on composing Python generators, which should help make the code easier to follow and more reusable.
def fib():
a, b = 0, 1
while True:
yield a
a, b = b, a + b
def evens(l):
for x in l:
if x % 2 == 0:
yield x
def sum_even_fibonacci(limit):
total = 0
for x in evens(fib()):
if total + x > limit:
return total
total += x
if __name__ == '__main__':
print(sum_even_fibonacci(4000000))
Output
1089154
Edit
It's ambiguous what exactly OP is asking.
If OP wants to sum the even Fibonacci terms until the sum would surpass 4,000,000, then the answer is what I stated above - 1089154.
If OP wants to sum all even Fibonacci terms under 4,000,000, then the expression if total + x > limit would change to x > limit and the answer would be 4613732.
x>limit
I recognize this as Problem 2 on Project Euler. For some reason, @Tagc is getting the wrong answer. I used a generator as well but not a list. Here was my solution:
def fibonacci():
term_0, term_1 = 1,2
while True:
yield term_0 + term_1
term_0, term_1 = term_1, term_0 + term_1
fibonacci_sum = 2
for n in fibonacci():
if n > 4000000: break
if n % 2 == 0: fibonacci_sum += n
print(fibonacci_sum)
Output:
$ python 002.py
4613732
total + x > limit to x > limit.
just for fun, this is an one liner version
from itertools import takewhile
def fib():
fk, fk1 = 0,1
while True:
yield fk
fk, fk1 = fk1, fk+fk1
print( sum( x for x in takewhile(lambda f:f<4000000,fib()) if x%2==0 ) )
here takewhile will stop the iteration when the condition is no longer satisfied the same way as the others answers
x=y; y= x+yis wrong.else: passis not necessary. Just remove it.4613732, not508186.