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Recognize an inline varying-coefficient bar

Source: R/formula.R
tulpa_is_spatial_bar.Rd

Test whether a one-sided formula carries a single varying-coefficient grouping bar of the form ~ 1 + w || node (independent fields, ||) or ~ 1 + w | node (correlated fields, |). This is the same grammar spatial() and the inline temporal() field constructor accept, and the grammar tulpa_bar_field_specs() expands. A downstream package can use it to branch on "is this term a spatial / temporal varying-coefficient bar?" before calling tulpa_bar_field_specs().

Usage

tulpa_is_spatial_bar(x)

Arguments

x

A one-sided formula (e.g. ~ 1 + w || node) or the bar language object itself (quote(1 + w || node)).

Value

A single logical: TRUE when x is (or wraps) a | / || bar, FALSE otherwise (a plain formula such as ~ 1 + w, a non-bar term, or a non-formula / non-language input).

See also

tulpa_bar_field_specs() for expanding the bar into per-column field specs.

Examples

tulpa_is_spatial_bar(~ 1 + w || cell)   # TRUE
tulpa_is_spatial_bar(~ 1 + w | cell)    # TRUE (correlated)
tulpa_is_spatial_bar(~ 1 + w)           # FALSE (no bar)