R/by-variable-utilities.R

In gavinsimpson/tsgam: Utilities for Working with GAMs Fitted to Time Series

##' Tests for by variable smooths
##'
##' Functions to check if a smooth is a by-variable one and to test of the type
##' of by-variable smooth is a factor-smooth or a continous-smooth interaction.
##'
##' @param smooth an object of class `"mgcv.smooth"`
##'
##' @return A logical vector.
##'
##' @author Gavin L. Simpson
##'
##' @export
##' @rdname is_by_smooth
`is_by_smooth` <- function(smooth) {
    check_is_mgcv_smooth(smooth)
    is_factor_by_smooth(smooth) | is_continuous_by_smooth(smooth)
}

##' @export
##' @rdname is_by_smooth
`is_factor_by_smooth` <- function(smooth) {
    check_is_mgcv_smooth(smooth)
    by.level <- smooth[["by.level"]]
    !is.null(by.level)
}

##' @export
##' @rdname is_by_smooth
`is_continuous_by_smooth` <- function(smooth) {
    check_is_mgcv_smooth(smooth)
    by.level <- by_level(smooth)
    by.var <- by_variable(smooth)
    !(is.null(by.level) & by.var == "NA")
}

##' @export
##' @rdname is_by_smooth
`by_variable` <- function(smooth) {
    check_is_mgcv_smooth(smooth)
    as.character(smooth[["by"]])
}

##' @export
##' @rdname is_by_smooth
`by_level` <- function(smooth) {
    check_is_mgcv_smooth(smooth)
    smooth[["by.level"]]
}