squaring doesn't seem to work
twiecki opened this issue · comments
I tried y ~ x**2 but it seemed like the squaring was ignored.
Hi @twiecki, you are right. If you want to square a variable you have to do y ~ I(x **2) or, using an alternative syntax, y ~ {x ** 2}. This is because ** is a valid operator for a set of terms.
For example, (a + b + c) ** 2 is equivalent to a + b + c + a:b + a:c + b:c.
PS: This is the same logic behind the addition between terms. If you want a term that is the sum of other two terms, you do I(x + y) or {x + y} instead of just x + y because the latter means you want to include x and y as separated terms.
We don't have it documented yet, but you can find it in Patsy docs here
Maybe a warning could be displayed if someone is doing `x**2` as that
doesn't seem to make sense for a single variable.
…On Sun, Mar 28, 2021 at 7:47 PM Tomás Capretto ***@***.***> wrote:
We don't have it documented yet, but you can find it in Patsy docs here
<https://patsy.readthedocs.io/en/latest/formulas.html#operators>
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Added warning in #13. Thanks for opening the issue!