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feat(arrow-array): add from_iter for DictionaryArray for building BinaryDictionaryArray #6922

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feat(arrow-array): add from_iter for DictionaryArray for building BinaryDictionaryArray #6922

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142 changes: 136 additions & 6 deletions arrow-array/src/array/dictionary_array.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,9 @@
// specific language governing permissions and limitations
// under the License.

use crate::builder::{PrimitiveDictionaryBuilder, StringDictionaryBuilder};
use crate::builder::{
BinaryDictionaryBuilder, PrimitiveDictionaryBuilder, StringDictionaryBuilder,
};
use crate::cast::AsArray;
use crate::iterator::ArrayIter;
use crate::types::*;
Expand Down Expand Up @@ -691,6 +693,61 @@ impl<'a, T: ArrowDictionaryKeyType> FromIterator<&'a str> for DictionaryArray<T>
}
}

/// Constructs a `DictionaryArray` from an iterator of optional bytes.
///
/// # Example:
/// ```
/// use arrow_array::{DictionaryArray, PrimitiveArray, BinaryArray, types::Int8Type};
///
/// let test: Vec<&[u8]> = vec![&[1, 3], &[4], &[2, 7], &[5, 6]];
/// let array: DictionaryArray<Int8Type> = test
/// .iter()
/// .map(|&x| if x == &[2, 7] { None } else { Some(x) })
/// .collect();
/// assert_eq!(
/// "DictionaryArray {keys: PrimitiveArray<Int8>\n[\n 0,\n 1,\n null,\n 2,\n] values: BinaryArray\n[\n [1, 3],\n [4],\n [5, 6],\n]}\n",
/// format!("{:?}", array)
/// );
/// ```
impl<'a, T: ArrowDictionaryKeyType> FromIterator<Option<&'a [u8]>> for DictionaryArray<T> {
fn from_iter<I: IntoIterator<Item = Option<&'a [u8]>>>(iter: I) -> Self {
let it = iter.into_iter();
let (lower, _) = it.size_hint();
let mut builder = BinaryDictionaryBuilder::with_capacity(lower, 256, 1024);
Comment on lines +712 to +716
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There is another FromIterator<Option<&'a str>> for DictionaryArray<T> for strings, which at first glance looks possible to combine. (Both use the GenericByteDictionaryBuilder with either strings, or bytes). Have you tried that, and do you think it's worthwhile?

builder.extend(it);
builder.finish()
}
}

/// Constructs a `DictionaryArray` from an iterator of bytes.
///
/// # Example:
///
/// ```
/// use arrow_array::{DictionaryArray, PrimitiveArray, BinaryArray, types::Int8Type};
///
/// let test: Vec<&[u8]> = vec![&[1, 3], &[4], &[2, 7], &[5, 6]];
/// let array: DictionaryArray<Int8Type> = test.into_iter().collect();
/// assert_eq!(
/// "DictionaryArray {keys: PrimitiveArray<Int8>\n[\n 0,\n 1,\n 2,\n 3,\n] values: BinaryArray\n[\n [1, 3],\n [4],\n [2, 7],\n [5, 6],\n]}\n",
/// format!("{:?}", array)
/// );
/// ```
impl<'a, T: ArrowDictionaryKeyType> FromIterator<&'a [u8]> for DictionaryArray<T> {
fn from_iter<I: IntoIterator<Item = &'a [u8]>>(iter: I) -> Self {
let it = iter.into_iter();
let (lower, _) = it.size_hint();
let mut builder = BinaryDictionaryBuilder::with_capacity(lower, 256, 1024);
it.for_each(|i| {
builder
.append(i)
.expect("Unable to append a value to a dictionary array.");
});
Comment on lines +741 to +745
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The Extend<Option<V>> uses append_option. Hence the two FromIterator impls here. 👍🏼


builder.finish()
}
}

impl<T: ArrowDictionaryKeyType> Array for DictionaryArray<T> {
fn as_any(&self) -> &dyn Any {
self
Expand Down Expand Up @@ -1193,7 +1250,7 @@ mod tests {
}

#[test]
fn test_dictionary_array_from_iter() {
fn test_string_dictionary_array_from_iter() {
let test = vec!["a", "a", "b", "c"];
let array: DictionaryArray<Int8Type> = test
.iter()
Expand All @@ -1211,6 +1268,25 @@ mod tests {
);
}

#[test]
fn test_binary_dictionary_array_from_iter() {
let test: Vec<&[u8]> = vec![&[1, 3], &[4], &[2, 7], &[5, 6]];
let array: DictionaryArray<Int8Type> = test
.iter()
.map(|&x| if x == [2, 7] { None } else { Some(x) })
.collect();
assert_eq!(
"DictionaryArray {keys: PrimitiveArray<Int8>\n[\n 0,\n 1,\n null,\n 2,\n] values: BinaryArray\n[\n [1, 3],\n [4],\n [5, 6],\n]}\n",
format!("{array:?}")
);

let array: DictionaryArray<Int8Type> = test.into_iter().collect();
assert_eq!(
"DictionaryArray {keys: PrimitiveArray<Int8>\n[\n 0,\n 1,\n 2,\n 3,\n] values: BinaryArray\n[\n [1, 3],\n [4],\n [2, 7],\n [5, 6],\n]}\n",
format!("{array:?}")
);
}

#[test]
fn test_dictionary_array_reverse_lookup_key() {
let test = vec!["a", "a", "b", "c"];
Expand All @@ -1227,7 +1303,7 @@ mod tests {
}

#[test]
fn test_dictionary_keys_as_primitive_array() {
fn test_string_dictionary_keys_as_primitive_array() {
let test = vec!["a", "b", "c", "a"];
let array: DictionaryArray<Int8Type> = test.into_iter().collect();

Expand All @@ -1238,7 +1314,23 @@ mod tests {
}

#[test]
fn test_dictionary_keys_as_primitive_array_with_null() {
fn test_binary_dictionary_keys_as_primitive_array() {
let test = vec![
"a".as_bytes(),
"b".as_bytes(),
"c".as_bytes(),
"a".as_bytes(),
];
let array: DictionaryArray<Int8Type> = test.into_iter().collect();

let keys = array.keys();
assert_eq!(&DataType::Int8, keys.data_type());
assert_eq!(0, keys.null_count());
assert_eq!(&[0, 1, 2, 0], keys.values());
}

#[test]
fn test_string_dictionary_keys_as_primitive_array_with_null() {
let test = vec![Some("a"), None, Some("b"), None, None, Some("a")];
let array: DictionaryArray<Int32Type> = test.into_iter().collect();

Expand All @@ -1259,8 +1351,46 @@ mod tests {
}

#[test]
fn test_dictionary_all_nulls() {
let test = vec![None, None, None];
fn test_binary_dictionary_keys_as_primitive_array_with_null() {
let test = vec![
Some("a".as_bytes()),
None,
Some("b".as_bytes()),
None,
None,
Some("a".as_bytes()),
];
let array: DictionaryArray<Int32Type> = test.into_iter().collect();

let keys = array.keys();
assert_eq!(&DataType::Int32, keys.data_type());
assert_eq!(3, keys.null_count());

assert!(keys.is_valid(0));
assert!(!keys.is_valid(1));
assert!(keys.is_valid(2));
assert!(!keys.is_valid(3));
assert!(!keys.is_valid(4));
assert!(keys.is_valid(5));

assert_eq!(0, keys.value(0));
assert_eq!(1, keys.value(2));
assert_eq!(0, keys.value(5));
}

#[test]
fn test_dictionary_all_string_nulls() {
let test: Vec<Option<&str>> = vec![None, None, None];
let array: DictionaryArray<Int32Type> = test.into_iter().collect();
array
.into_data()
.validate_full()
.expect("All null array has valid array data");
}

#[test]
fn test_dictionary_all_binary_nulls() {
let test: Vec<Option<&[u8]>> = vec![None, None, None];
let array: DictionaryArray<Int32Type> = test.into_iter().collect();
array
.into_data()
Expand Down
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