Why anovan does not accept p = anovan(y) like anova1?

The dataset that I have has different numbr of smaples so I need to do unbiased ANOVA test. I realized that anovan does not accept only y like what anova1 does:

p = anova1(y)

For anovan I need to have group like:

p = anovan(y,group)

Any idea why?

[Sindar]

"anova1(y) treats each column of y as a separate group" what would be the default grouping for anovan(y)?

[Zeynab Mousavikhamene]

@sindar That's kind of my question.

[Sindar]

Honestly, I have no idea what an ANOVA test is, but it seems like anovan requires multiple groupings. Each element of a matrix is associated with three values: element value, row index, column index. If you only need one grouping, you could use either row or column index. But, if you need more than one, your only choice would be to use both row and column, but this would result in every element having a unique pair of groups, which perhaps doesn't make sense for the problem? Thus, there is no good default grouping and the function needs you to set one manually