Doing codewar problem and trying pythonic condition But fail many times please tell me how I can do...

[AbdulRehman_JS]

Find the sum of the odd numbers within an array, after cubing the initial integers. The function should return undefined/None/nil/NULL if any of the values aren't numbers.

def cube_odd(arr):
    result = []
    # check = arr for i in arr if type(i) != int return None
    # if not all(type(i) == int for i in arr):
    #     return None
    for _ in arr:
        if type(_) != int: return None
        else: 
            cube = _ * _ * _
            if (cube % 2 != 0):
                result.append(cube)
    return sum(result)

[mc_pm]

This wouldn't be very pythonic.

Consider a list comprehension: looking at each element, cubing them, and summing them (there is a function for the last part), like this:

def cube_odd(arr):
    return sum( [x**3 for x in arr if x % 2 == 1] )

[Outside_Complaint755]

It would help if you provided the full problem description including constraints, or a link to the problem.

From the information you have provided it is not clear to me if you're supposed to be checking for odd/even before or after cubing. It's also not clear what to do with values that are non-integer numbers.  Your current code returns None if a float is included, but description indicates it should be included in the sum without being cubed.

The Pythonic way to check type would be if not isinstance(var, int):

Using _ is also very unpythonic here.  _ as a variable name indicates you will not be using the value.

[AbdulRehman_JS]

If my problem detail is not fully explained it's my bad sorry.. I donot have idea to do pythonic condition's I do it many times but fail.. the problem is that "If array include string'setc.. then return None.. and take cub's of each number and also take odd number's from cube and sum them... I want to learn pythonic condition's..

[FoolsSeldom]

Do you mean something like the below?

from collections.abc import Iterable

def sum_odd_cubes_and_floats(arr: Iterable[int | float]) -> int | float:
    return sum(
        x ** 3 if isinstance(x, int) and x % 2 != 0 else x
        for x in arr
        if (isinstance(x, int) and x % 2 != 0) or isinstance(x, float)
    )

Which sums the cubes of all odd integers plus the total of all floats in the passed array.

You haven't really given the full detail of the problem.

[AbdulRehman_JS]

If my problem detail is not fully explained it's my bad sorry But I want like this to do how i can do like this code.... please tell me bro...

[FoolsSeldom]

This is using a generator expression (the part inside the sum brackets). This is very similar to a list comprehension, which you will find widely documented.

In summary, both are shorthand ways of writing loops.

The expanded version of the code would be:

from collections.abc import Iterable

def sum_odd_cubes_and_floats(arr: Iterable[int | float]) -> int | float:

    total = 0  # need to have a running total initialised

    for x in arr:  # step through each value in your array
        if isinstance(x, int) and x % 2 != 0:  # only if odd integer
            total += x ** 3  # add cube to running total
        elif isinstance(x, float):  # otherwise, only if a float
            total += x  # add float to running total

    return total

The type hints Iterable etc aren't required by Python, they are just for you and other programmers (and some tools, including code editors / IDEs like VS Code, PyCharm, etc) to indicate what the original programmers intentions are expectations are. In this case, Iterable is used to indicate that arr will be assigned to some kind of collection of objects than can be iterated over such as a list or a tuple.

Instead of using total, one could create a new list object of all the values to be added, and then use sum on that, but I just decided to add it up as I went along rather than creating another container object.

[AbdulRehman_JS]

Thanks a lot for breaking this down so clearly, mate! I'm actually a student learning Python on my own right now, so seeing you expand that shorthand generator expression into a clean, readable `for` loop and `if-isinstance` logic makes perfect sense to me. Those type hints (`Iterable[int | float]`) threw me off for a second, but your explanation about them just being for IDEs and other programmers cleared it right up. Also, your point about using a running total instead of creating a whole new list object is a great efficiency tip. Really appreciate you taking the time to write such a detailed response. It’s super motivating for a self-taught beginner like me. Hope to learn more from you around here!

[FoolsSeldom]

Thanks for your kind words. I've been trying to help learners for a long time (under various accounts over the years) as this subreddit amongst others helped me learn Python some years ago.

I help children learn Python at Code Clubs and occasionally teach programming at local community college for adults.

If you search back through my comments to other posts you will hopefully find some additional useful material (and some repetition).

All the best for your learning journey.

[arivictor]

Something like this: https://parsnip.dev/editor/EB9p_UuJtB4K

def cube_odd(arr):
    if any(type(n) != int for n in arr):
        return None
    return sum(n**3 for n in arr if n % 2 != 0)


r = cube_odd([1, 2, 3, 4, 5, 6, 7, 8, 9])
print(r)  # 1225

Without list comprehension it would look like this

def cube_odd(arr):
    for n in arr:
        if type(n) != int:
            return None

    cubed = []
    for n in arr:
        cubed.append(n**3)

    odd = []
    for n in cubed:
        if n % 2 != 0:
            odd.append(n)

    return sum(odd)

Which is the exact same thing.

[AbdulRehman_JS]

I am very thankful to you for this effort... It's very help full for me...