brk_cFilterFD: Function used to filter functional data in sf objects.
In briskaR: Biological Risk Assessment

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`	sf. An object of class sf
`key`	character string. The name of the column to select
`index`	integer (or vector). The index of the functional data.
`key1`	character string. The name of the column to select
`key2`	character string. The name of the column to select
`key3`	character string. The name of the column to select