Formula

class brmp.formula.Formula(response, terms, groups)

Represents an lme4 formula.

~ A valid formula contains exactly one occurrence of ~ . The LHS gives the name of the scalar response variable. The RHS describes the structure of the model.
+ A combination of terms.
: An interaction between two terms. Can also appear on the RHS of | or || to specify grouping by multiple factors.
| Introduces a group-level term. (i.e. random effect.)
|| Introduces a group-level term, omitting modelling of group-level correlations.
1 Intercept term. Note that intercept terms are not added automatically.

The following examples are all parsed as valid formulae:

y ~ x
y ~ 1 + x
y ~ 1 + x1:x2
y ~ 1 + x1 + (1 + x2 | a)
y ~ 1 + x1 + (1 + x2 || a:b)