formula_poly("z", 2)
formula_poly("z", 2, noint=TRUE)
as_rhs_chr(c("a", "b", "z"))
as_rhs_chr(c("a*b", "z"))
as_rhs_chr(y~a+b+z)
as_rhs_chr(y~a+b+z, string=TRUE)
as_rhs_chr(y~a+b+z)
as_rhs_chr(y~a*b+z)
as_rhs_chr(y~a*b+z, string=TRUE)
as_lhs_chr(y~a*b+z)
as_lhs_chr(log(y)~a*b+z) ## Not what one might expect
as_lhs_chr(cbind(y, u)~a*b+z) ## Not what one might expect
formula_chr_to_form(c("a*b", "z"))
formula_chr_to_form(c("a*b", "z"), "y")
formula_chr_to_form(c("a*b", "z"), "log(y)")
formula_add(y~a*b+z, ~-1)
formula_add(y~a*b+z, ~a:b)
formula_add_str(y~x1 + x2, "x3")
formula_add_str(y~x1 + x2, "x1")
formula_add_str(y~x1 + x2, "x1", op="-")
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