Mathematical Notation for mean of a variable in a class

28 Views Asked by At

I would ask for your help.

How can I write down in mathematical notation the average for a specific feature that has a specific class.

For example, in a dataset with two features: a continues HEIGHT, and a binary target GENDER with two classes MALE and FEMALE, I would like to calculate the average of the HEIGHT separately for MALE and FEMALE.

I have done the below so far, but, I think, I don't really highlight that this calculation should be done for each class:

$$ {mean}_{ac} = \frac{1}{n_c} \sum_{i=1}^{n} x_{i} $$

I wondered if I need to emphasise that I do this for all the points that have the specific class, something like:

yi = c

Thanks.