Add support for arrow2::types::f16 (#104)

* Add support for arrow2::types::f16

* Add a few more exotic values for half round-trip

* cargo fmt

Author: jleibs

arrow2_convert/src/deserialize.rs

@@ -114,6 +114,7 @@ impl_arrow_deserialize_primitive!(i8);
 impl_arrow_deserialize_primitive!(i16);
 impl_arrow_deserialize_primitive!(i32);
 impl_arrow_deserialize_primitive!(i64);
+impl_arrow_deserialize_primitive!(arrow2::types::f16);
 impl_arrow_deserialize_primitive!(f32);
 impl_arrow_deserialize_primitive!(f64);
 

arrow2_convert/src/field.rs

@@ -110,6 +110,7 @@ impl_numeric_type_full!(i8, Int8);
 impl_numeric_type_full!(i16, Int16);
 impl_numeric_type_full!(i32, Int32);
 impl_numeric_type_full!(i64, Int64);
+impl_numeric_type_full!(arrow2::types::f16, Float16);
 impl_numeric_type_full!(f32, Float32);
 impl_numeric_type_full!(f64, Float64);
 

arrow2_convert/src/serialize.rs

@@ -86,6 +86,7 @@ impl_numeric_type!(i8);
 impl_numeric_type!(i16);
 impl_numeric_type!(i32);
 impl_numeric_type!(i64);
+impl_numeric_type!(arrow2::types::f16);
 impl_numeric_type!(f32);
 impl_numeric_type!(f64);
 

arrow2_convert/tests/test_round_trip.rs

@@ -9,6 +9,7 @@ use arrow2_convert::{
     ArrowDeserialize, ArrowField, ArrowSerialize,
 };
 use std::borrow::Borrow;
+use std::f32::INFINITY;
 use std::sync::Arc;
 
 #[test]
@@ -194,6 +195,34 @@ fn test_primitive_type_vec() {
     test_float_type!(f32);
     test_float_type!(f64);
 
+    // `arrow2::types::f16` isn't a native type so we can't just use `as`
+    {
+        let original_array: Vec<arrow2::types::f16> =
+            vec![1.0, 2.5, 47800.0, 0.000012, -0.0, 0.0, INFINITY]
+                .iter()
+                .map(|f| arrow2::types::f16::from_f32(*f))
+                .collect();
+        let b: Box<dyn Array> = original_array.try_into_arrow().unwrap();
+        let round_trip: Vec<arrow2::types::f16> = b.try_into_collection().unwrap();
+        assert_eq!(original_array, round_trip);
+
+        let original_array: Vec<Option<arrow2::types::f16>> = vec![Some(1.), None, Some(3.)]
+            .iter()
+            .map(|f| f.map(arrow2::types::f16::from_f32))
+            .collect();
+        let b: Box<dyn Array> = original_array.try_into_arrow().unwrap();
+        let round_trip: Vec<Option<arrow2::types::f16>> = b.try_into_collection().unwrap();
+        assert_eq!(original_array, round_trip);
+
+        let original_array: Vec<Option<arrow2::types::f16>> = vec![Some(1.), None, Some(3.)]
+            .iter()
+            .map(|f| f.map(arrow2::types::f16::from_f32))
+            .collect();
+        let b: Arc<dyn Array> = original_array.try_into_arrow().unwrap();
+        let round_trip: Vec<Option<arrow2::types::f16>> = b.try_into_collection().unwrap();
+        assert_eq!(original_array, round_trip);
+    };
+
     // i128
     // i128 is special since we need to require precision and scale so the TryIntoArrow trait
     // is not implemented for Vec<i128>.