Function used to filter functional data in sf objects.
brk_cFilterFD(sf, key, index)brk_cFilterFD_(sf, key, index)
brk_cFilterFD2(sf, key1, key2, index)
brk_cFilterFD3(sf, key1, key2, key3, index)
sf. An object of class sf
character string. The name of the column to select
integer (or vector). The index of the functional data.
character string. The name of the column to select
character string. The name of the column to select
character string. The name of the column to select