prime number function python from list

Question

Below is my code to make a prime number list from Fibonacci list, but the prime list is not working.

what am I missing? I need to make a prime number list from Fibonacci list.

a1 = []
a2 = []
count = 0
n = int(input())


def fib(n):
    a = 1
    b = 1
    a1.append(a)
    a1.append(b)
    for i in range(n):
        c = a + b
        a = b
        b = c
        if len(a1) <= n - 1:
            a1.append(c)
    print(a1)
    print(len(a1))


fib(n)


def pr(a1):
    count = 0
    for i in a1:
        for j in range(2, i):
            if i % j == 0:
                count += 1
        if count > 0:
            a2.append()
    print(a2)

why the prime number list not working?

Answer 1

I made some fixes to your code:

def fib(n):
    a = 1
    b = 2
    a1.append(a)
    a1.append(b)
    for i in range(n):
        c=a+b
        a=b
        b=c
        if len(a1)<=n-1:
            a1.append(c)
    print(a1)
    print(len(a1))
    

def pr(a1):
    for i in a1:
        isPrime = True
        for j in range(2,i):
            if i % j == 0:
                isPrime = False
                break
        if isPrime:
            a2.append(i)
            
    print(a2)

a1=[]
a2=[]
n=int(input())
fib(n)
pr(a1)

1. You never called the function pr() . It seems a bit, like you are not quite sure how functions work, maybe read a bit into them (or just ask away:) )
2. Since you already append a and b anyway, why not start them of with the correct fibonacci sequence (1, 2,..) to avoid duplicates?
3. I changed the code to find prime numbers a bit, to make it a tiny bit faster. I'm sure this is by no means the optimized, but at least it immedately breaks the loop, if it is clear, that we don't have a prime number.
4. In pr() you used the append() method without an argument. You need to tell the program what you want to append to the list. As far as I can tell this is, where you got an exception.

Hope this helps a bit.

Answer 2

Try the below code. Edited your code and a2 will give prime numbers in the fibonacci list.

a1 = []
    a2 = []
    
    def recur_fibo(n):
       if n <= 1:
           return n
       else:
           return(recur_fibo(n-1) + recur_fibo(n-2))
    
    n = 10
    
    if n > 0:
       for i in range(n):
           a1.append(recur_fibo(i))
    
    for num in a1:
      if num > 1:
        for i in range(2,num):
            if (num % i) == 0:
                break
        else:
            a2.append(num)
    
    print(a2)