This function supports parsing
the formula to extract into its parts
is it an error not to have groups?
is it an error to have a one-sided formula?
This function extracts the left hand side (
lhs), right hand
rhs), groups (
groups and as a formula,
grpFormula), the environment (
env, and the original
left/right hand side of the model (
This function borrows heavily from the
function in the doBy package.
A parseFormula class list with elements of
The left~right side of the model (excluding groups)
The call for the left hand side
The call for the right hand side (excluding groups)
The call for the groups
A formula form of the groups
The original formula's environment
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