Python Forum

I'm going through refactoring and cleaning up my code.

At the moment, I have data written to a file to store it, then later on I take the file and create two lists out of the data.
One list is multiple lists of 3 rgb values:
rgb = [[55,35,133],[54,75,34],[,122,186,55],[42,134,5],[22,4,145]...]
and one is a list of absolute paths to the images.
Each are 30,000 items longs.

As I'm refactoring, to remove the use of any files, and only have one list, I thought about creating a simple class like this:

class CustomImage(): #my custom image class
    def __init__(self, name, path, size, rgb, ext="png"):
        self.name = name
        self.path = path
        self.size = size
        self.ext = ext
        self.avg = rgb
    @property
    def rgb(self):
        return self.avg
    @property
    def size(self):
        return self.size
    @property
    def path(self):
        return self.path
    @property
    def name(self):
        return self.name
    @property
    def ext(self):
        return self.ext

Once I have downloaded an image, I simply create a "CustomImage" out of that image, which I can easily use later in my code. I would store all the these "CustomImages" in a list (also of 30,000 items)

What would be most likely to take up more memory? I would test it but I'm not sure about how I can measure list sizes in memory.

Found out how to test it:
The two lists take up a total of 507,248 bytes in memory.

The class, which has become:

class CustomImage(): #my custom image class
    def __init__(self, name, path, size, rgb, ext="png"):
        self.name = name
        self.path = path
        self.size = size
        self.ext = ext
        self.avg = rgb

takes up only 253,624 bytes in an array of 30,000

Since each image always has the same attributes, you could save even more space using slots. Classes that use slots instead of __dict___ provide faster access and have a smaller memory footprint.

class CustomImage(): #my custom image class
    __slots__ = 'name', 'path', 'size', 'ext', 'avg'
    def __init__(self, name, path, size, rgb, ext="png"):
        self.name = name
        self.path = path
        self.size = size
        self.ext = ext
        self.avg = rgb

With slots you cannot add an attribute to the class. You can access or set attribute values, but I could not do custimg.rating = 4 because there is no slot for "rating".
If CustomImage is immutable you could also use a named tuple (import collections).

DreamingInsanity

deanhystad