CODEWITHSUNDEEP
pythoncollatz
username
username

Reputation: 37

How do I input a list into a function and recieve a list in Python?

I am trying to make code that takes a list of numbers starting from a billion to 2 billion with an increment of 100 million and outputs a list of the number of steps it takes to reach one using the Collatz conjecture for each number.

My code:

from math import pow


# Defining the function
def collatz(the_input):
    step = 1
    while the_input > 1:
        if (the_input % 2) == 0:
            the_input = the_input / 2
        else:
            the_input = ((the_input * 3) + 1) / 2
        step += 1
    return step


the_inputs = []
the_number = pow(10, 9)
increment = pow(10, 8)

while the_number <= 2 * pow(10, 9):
    the_inputs.append(the_number)
    the_number += increment
print(the_inputs)

Upvotes: 0

Views: 468

Answers (3)

Apo
Apo

Reputation: 338

You can Create a list of all your input like :

inputs = [k for k in range(pow(10,9),2*pow(10,9),pow(10,8))]

And iterate for each element of your list:

outputs = []
for input in inputs :
    outputs.append(collatz(input))
print(outputs)

Upvotes: 0

Aplet123
Aplet123

Reputation: 35540

Loop through the list:

for num in the_inputs:
    steps = collatz(num)
    print(f"it takes {steps} steps for {num}")

This code uses f-strings.

Or, use a list comprehension for a list:

step_list = [collatz(num) for num in the_inputs)]

Upvotes: 1

Grismar
Grismar

Reputation: 31354

A version of your collatz function for lists:

def collatz_list(numbers):
    result = []
    for number in numbers:
        step = 1
        while number > 1:
            if (number % 2) == 0:
                number = number / 2
            else:
                number = ((number * 3) + 1) / 2
            step += 1
        result.append(step)
    return result

Or you could just reuse your function like this:

result = [collatz(number) for number in the_inputs]

Upvotes: 0

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