Creates a query selection for use inside a named list passed to
pxweb_query or pxweb_get. This is useful when a
PXWEB table requires an explicit API filter such as an aggregation or value
set filter.
Examples
query <- list(
alue_23_20260101 = pxweb_selection("agg:_Regions 2026.agg", "MK01"),
timeperiod_y = "2025"
)
pxq <- pxweb_query(query)
