Sparse Table

The SparseTable domain provides a general purpose table type with default entries.

Here we create a table to save strings under integer keys. The value “Try again!” is returned if no other value has been stored for a key.

t: SparseTable(Integer, String, "Try again!") := table()
  table()
                         Type: SparseTable(Integer,String,Try again!)

Entries can be stored in the table.

t.3 := "Number three"
  "Number three"
                         Type: String

t.4 := "Number four"
  "Number four"
                         Type: String

These values can be retrieved as usual, but if a look up fails the default entry will be returned.

t.3
  "Number three"
                         Type: String

t.2
  "Try again!"
                         Type: String

To see which values are explicitly stored, the keys and entries functions can be used.

keys t
  [4,3]
                         Type: List Integer

entries t
  ["Number four","Number three"]
                         Type: List String

If a specific table representation is required, the GeneralSparseTable constructor should be used. The domain SparseTable(K, E, dflt)} is equivalent to GeneralSparseTable(K,E,Table(K,E), dflt).

See Also:

• )help Table
• )help GeneralSparseTable
• )show SparseTable