Renaming include_background

[wyli]

Discussed in #6915

^{Originally posted by ellisdg August 30, 2023}
In many of the loss classes and metrics in MONAI, the creators have put in an argument named include_background. To my understanding, what this argument does is include the first channel in the computations, if True, and exclude the first channel in the computations, if False.

I have a few issues with the naming of the include_background argument:

1. The name is ambiguous and does not reflect what the argument actually does.
2. The background channel could be any of the channels, and does not necessarily have to be the first channel.
3. When there is no background channel, you should specify include_background=True, which is counter-intuitive because there is no background to be included.

Therefore, why isn't the argument called include_first_channel instead? This name says what the include_background argument actually does.

would be great to rename it to include_zeroth_channel or include_channel_zero, while keeping the existing name for backward compatibility for two versions.

[myron]

I think it almost does not matter, to me, the existing name and the new proposed name both are clear. I'll be ok either way, but we've already got used to the current names, which were there for years..
#7056 (comment)

[vikashg]

closing will reopen if further discussion is needed.