Wolfram: List. Select (Filter)

Filter by Function

Select

• Select[ expr, function ] → Get elements by a filter function
• Select[ expr, function, n ] → return first n items.

• Select

Select[ {3,4,5,6}, EvenQ ]

(* {4, 6} *)

Select[ {{3}, {0, 23}, {9}, {4,5,6}}, Function[ Length[#] === 2 ] ]

(* {{0, 23}} *)

Filter by Pattern

• Wolfram: List. Cases (Filter by pattern)