minor: make dict_from_values public

[parthchandra]

Which issue does this PR close?

• Closes make dict_from_values public #17366.

Rationale for this change

reduce code duplication in Datafusion Comet.

What changes are included in this PR?

Makes the method public

Are these changes tested?

Existing tests

Are there any user-facing changes?

No

[comphead]

Thanks @parthchandra please check if proposed method description is accurate enough

[parthchandra]

Thanks @parthchandra please check if proposed method description is accurate enough

Shouldn't that be -

/// # Input
/// ["alice", "bob", "alice", null, "carol"]
/// 
/// # Output
/// DictionaryArray<Int32>
/// {
///   keys:   [0, 1, 0, null, 2],
///   values: ["alice", "bob", "carol"]
/// }

[comphead]

Thanks @parthchandra please check if proposed method description is accurate enough

Shouldn't that be -

/// # Input
/// ["alice", "bob", "alice", null, "carol"]
/// 
/// # Output
/// DictionaryArray<Int32>
/// {
///   keys:   [0, 1, 0, null, 2],
///   values: ["alice", "bob", "carol"]
/// }

I dont think so, as there is no dict conversions, just a loop, but I ran a test

    #[test]
    fn test_dict_from_values_with_strings() {
        let values = Arc::new(StringArray::from(vec!["a", "b", "a", "c"])) as ArrayRef;
        let dict = dict_from_values::<Int32Type>(values).unwrap();
        dbg!(&dict);
    }

[datafusion/common/src/scalar/mod.rs:7650:9] &dict = DictionaryArray {keys: PrimitiveArray<Int32>
[
  0,
  1,
  2,
  3,
] values: StringArray
[
  "a",
  "b",
  "a",
  "c",
]}

[parthchandra]

I dont think so, as there is no dict conversions, just a loop, but I ran a test
Ah, I see now that there is no de-duping. I've applied the comment change.

[comphead]

Thanks @parthchandra