9.73 SparseTable

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"

\[\]

“Numberthree”

_{Type: String}

t.4 := "Number four"

\[\]

“Numberfour”

_{Type: String}

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

t.3

\[\]

“Numberthree”

_{Type: String}

t.2

\[\]

“Tryagain!”

_{Type: String}

To see which values are explicitly stored, the keyskeysSparseTable and entriesentriesSparseTable functions can be used.

keys t

\[\]

[4,3]

_{Type: List Integer}

entries t

\[\]

[“Numberfour”,”Numberthree”]

_{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). For more information, see TableXmpPage and GeneralSparseTableXmpPage .