FormulaSelection: Limit matrix or data frame to selected model terms

In statisticsnorway/SSBtools: Statistics Norway's Miscellaneous Tools

Limit matrix or data frame to selected model terms

Description

For use with output from ModelMatrix or data frames derived from such output.

Usage

FormulaSelection(x, formula, intercept = NA)

formula_selection(x, formula, intercept = NA)

Arguments

x	Model matrix or a data frame
formula	Formula representing the limitation or character string(s) to be converted to a formula (see details)
intercept	Parameter that specifies whether a possible intercept term (overall total) should be included in the output. Default is TRUE when a formula is input. Otherwise, see details.

Details

The selection is based on startCol or startRow attribute in input x.

With formula as character:

• ~ is included: Input is converted by as.formula and default intercept is TRUE.

• ~ is not included: Internally, input data is converted to a formula by adding ~ and possibly +'s when the length is ⁠>1⁠. Default intercept is FALSE unless "1" or "(Intercept)" (is changed internally to "1") is included.

Value

Limited model matrix or a data frame

Note

formula_selection and FormulaSelection are identical

Examples

z <- SSBtoolsData("sprt_emp_withEU")
z$age[z$age == "Y15-29"] <- "young"
z$age[z$age == "Y30-64"] <- "old"

x <- ModelMatrix(z, formula = ~age * year)

FormulaSelection(x, "age")
FormulaSelection(x, ~year)
FormulaSelection(x, ~year:age)

# x1, x2, x3, x4 and x4 are identical
x1 <- FormulaSelection(x, ~age)
x2 <- FormulaSelection(x, "~age")
x3 <- FormulaSelection(x, "age", intercept = TRUE)
x4 <- FormulaSelection(x, c("1", "age"))
x5 <- FormulaSelection(x, c("(Intercept)", "age"))


a <- ModelMatrix(z, formula = ~age * geo + year, crossTable = TRUE)
b <- cbind(as.data.frame(a$crossTable), 
           sum = (t(a$modelMatrix) %*% z$ths_per)[, 1], 
           max = DummyApply(a$modelMatrix, 
           z$ths_per, max))
rownames(b) <- NULL
attr(b, "startRow") <- attr(a$modelMatrix, "startCol", exact = TRUE)

FormulaSelection(b, ~geo * age)
FormulaSelection(b, "age:geo")
FormulaSelection(b, ~year - 1)

statisticsnorway/SSBtools documentation built on Jan. 17, 2024, 3:40 p.m.