picks out those elements of list for which the corresponding element of sel matches patt.
- sel can be a nested list of any depth.
- Pick[list,sel,patt] picks out those list[[i1,i2,…]] for which sel[[i1,i2,…]] matches patt.
- Depending on the arrangement of elements matching patt in a nested list sel, Pick may return a ragged array.
- The heads in list and sel do not have to be List.
- Pick works with SparseArray objects.
Introduced in 2004