Split a list into even and odd numbers

Python
1

I’m having trouble trying to split a list into even and odd numbers with the variables odd and even representing their respective numbers.

The professor noted that this line of code:

odd, even = foo([1,2,3,4,5,6], lambda x : x % 2 == 0)

Should split the numbers into odd and even. How do I do something like this? I know how to filter between odd and even numbers, but I’m unsure of how to set two variables in one line equal to their respective parts.
In your example foo is a function, and returns a pair of variables. For example:

def foo():
    a = 1
    b = 2
    return (a, b)

x, y = foo()  # x is now '1', and y is now '2'

So you need to create a function that iterates over the input list, and assigns the elements to either an odd list or an even list. Then return both of these lists, as the above example.
For Reference use the below links

2

I’m having trouble trying to split a list into even and odd numbers with the variables odd and even representing their respective numbers.

The professor noted that this line of code:

odd, even = foo([1,2,3,4,5,6], lambda x : x % 2 == 0)

Should split the numbers into odd and even. How do I do something like this? I know how to filter between odd and even numbers, but I’m unsure of how to set two variables in one line equal to their respective parts.
In your example foo is a function, and returns a pair of variables. For example:

def foo():
    a = 1
    b = 2
    return (a, b)

x, y = foo()  # x is now '1', and y is now '2'

So you need to create a function that iterates over the input list, and assigns the elements to either an odd list or an even list.

Python-programming-for-hackers-compressed
Python-programming-for-hackers-compressed1395×864 80.5 KB

4

Well, i just start tinkering with Python so I’ll try this one!

This is what i came up with ( a bit verbose but clear i think):

def splitOddEven(number_list):
	"""it separate a list of numbers into odd and even"""
	odd_list = [];
	even_list = [];
	while(number_list):
		current_number = number_list.pop();
		if(current_number % 2 == 0):
			even_list.append(current_number)
		else:
			odd_list.append(current_number)
	
	return (even_list, odd_list)
	
test_list = [2,3,1,5,78,32,121,12]
even, odd = splitOddEven(test_list[:])

print("These are the even numbers of your list:" + str(even))
print("\nThese are the odd numbers of your list: " + str(odd))

If this was your doubt

I’m unsure of how to set two variables in one line equal to their respective parts.

looks like is just a positional matter^^

5

There’s a number of ways to do this. You could create a function that specifically splits a list into even and odd sets. However, the way your professor set up this code:

odd, even = foo([1,2,3,4,5,6], lambda x : x % 2 == 0)

Makes me believe they are attempting to get you to think a little more broadly by creating a function that accepts a list and a callback function (a simple True or False lambda function in this case) as arguments and returns the True/False lists.

Let’s start with the lambda function your professor gave and figure out what it’s doing:

splitter_function = lambda x: x % 2 == 0
# This has assigned the lambda function to the variable splitter_function so we can test it
# splitter_function accepts a number as an argument and returns True or False
# depending on if the number is even (True) or odd (False)
print(splitter_function(5))
# False
print(splitter_function(4))
# True

Okay, so knowing that, we need a function foo() that accepts a list of numbers and applies a True/False callback function to each number then appends them to an appropriate list for return.

def foo(list_of_numbers, splitter_function):
    """Function that accepts a list of numbers and splits them into
       truthy and falsy lists based upon the callback function argument"""
    f = []  # Falsy list
    t = []  # Truthy list
    for number in list_of_numbers:
        if splitter_function(number):
            t.append(number)
            # If splitter_function returns True --> append number to list t
        else:
            f.append(number)
            # Else if splitter_function returns False --> append number to list f
    return (f, t)  # Return the lists, Falsy (odd potentially) first, then Truthy (even potentially)

Now to use it:

print(foo([1, 2, 3, 4, 5, 6], lambda x: x % 2 == 0))
# ([1, 3, 5], [2, 4, 6])

odd, even = foo([1, 2, 3, 4, 5, 6], lambda x: x % 2 == 0)
print(odd)
#[1, 3, 5]
print(even)
# [2, 4, 6]

# This can also be used to check if numbers are divisible by numbers other than 2 as well
not_divisible, divisible = foo([1, 2, 3, 4, 5, 6], lambda x: x % 3 == 0)
print(not_divisible)
# [1, 2, 4, 5]
print(divisible)
# [3, 6]

Hope that helps.

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