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use arrow2::{
array::{
growable::make_growable, Array, FixedSizeListArray, ListArray, StructArray, UnionArray,
},
bitmap::Bitmap,
datatypes::{DataType, Field, UnionMode},
offset::Offsets,
};
use itertools::Itertools;
// ---
pub trait ArrayExt: Array {
/// Returns the length of the child array at the given index.
///
/// * Panics if `self` is not a `ListArray<i32>`.
/// * Panics if `child_nr` is out of bounds.
fn get_child_length(&self, child_nr: usize) -> usize;
/// Create a new `Array` which avoids problematic types for polars.
///
/// This does the following conversion:
/// - `FixedSizeList` -> `List`
/// - `Union` -> `Struct`
///
/// Nested types are expanded and cleaned recursively
fn clean_for_polars(&self) -> Box<dyn Array>;
}
impl ArrayExt for dyn Array {
/// Return the length of the first child.
///
/// ## Panics
///
/// Panics if `Self` is not a `ListArray<i32>`, or if the array is empty (no children).
fn get_child_length(&self, child_nr: usize) -> usize {
self.as_any()
.downcast_ref::<ListArray<i32>>()
.unwrap()
.offsets()
.lengths()
.nth(child_nr)
.unwrap()
}
/// Create a new `Array` which avoids problematic types for polars.
///
/// This does the following conversion:
/// - `FixedSizeList` -> `List`
/// - `Union` -> `Struct`
///
/// Nested types are expanded and cleaned recursively
fn clean_for_polars(&self) -> Box<dyn Array> {
let datatype = self.data_type();
let datatype = if let DataType::Extension(_, inner, _) = datatype {
(**inner).clone()
} else {
datatype.clone()
};
match &datatype {
DataType::List(field) => {
// Recursively clean the contents
let typed_arr = self.as_any().downcast_ref::<ListArray<i32>>().unwrap();
let clean_vals = typed_arr.values().as_ref().clean_for_polars();
let clean_data = DataType::List(Box::new(Field::new(
&field.name,
clean_vals.data_type().clone(),
field.is_nullable,
)));
ListArray::<i32>::try_new(
clean_data,
typed_arr.offsets().clone(),
clean_vals,
typed_arr.validity().cloned(),
)
.unwrap()
.boxed()
}
DataType::LargeList(field) => {
// Recursively clean the contents
let typed_arr = self.as_any().downcast_ref::<ListArray<i64>>().unwrap();
let clean_vals = typed_arr.values().as_ref().clean_for_polars();
let clean_data = DataType::LargeList(Box::new(Field::new(
&field.name,
clean_vals.data_type().clone(),
field.is_nullable,
)));
ListArray::<i64>::try_new(
clean_data,
typed_arr.offsets().clone(),
clean_vals,
typed_arr.validity().cloned(),
)
.unwrap()
.boxed()
}
DataType::FixedSizeList(field, len) => {
// Recursively clean the contents and convert `FixedSizeListArray` -> `ListArray`
let typed_arr = self.as_any().downcast_ref::<FixedSizeListArray>().unwrap();
let clean_vals = typed_arr.values().as_ref().clean_for_polars();
let clean_data = DataType::List(Box::new(Field::new(
&field.name,
clean_vals.data_type().clone(),
field.is_nullable,
)));
let lengths = std::iter::repeat(len).take(typed_arr.len()).cloned();
let offsets = Offsets::try_from_lengths(lengths).unwrap();
ListArray::<i32>::try_new(
clean_data,
offsets.into(),
clean_vals,
typed_arr.validity().cloned(),
)
.unwrap()
.boxed()
}
DataType::Struct(fields) => {
// Recursively clean the contents
let typed_arr = self.as_any().downcast_ref::<StructArray>().unwrap();
let clean_vals = typed_arr
.values()
.iter()
.map(|v| v.as_ref().clean_for_polars())
.collect_vec();
let clean_fields = itertools::izip!(fields, &clean_vals)
.map(|(f, v)| Field::new(&f.name, v.data_type().clone(), f.is_nullable))
.collect_vec();
let clean_data = DataType::Struct(clean_fields);
StructArray::try_new(clean_data, clean_vals, typed_arr.validity().cloned())
.unwrap()
.boxed()
}
DataType::Union(fields, ids, UnionMode::Dense) => {
// Recursively clean the contents and convert `UnionArray` -> `StructArray`
let typed_arr = self.as_any().downcast_ref::<UnionArray>().unwrap();
// Note: Union calls its stored value-arrays "fields"
let clean_vals = typed_arr
.fields()
.iter()
.map(|v| v.as_ref().clean_for_polars())
.collect_vec();
let ids = ids
.clone()
.unwrap_or_else(|| (0i32..(clean_vals.len() as i32)).collect_vec());
// For Dense Unions, the value-arrays need to be padded to the
// correct length, which we do by growing using the existing type
// table.
let padded_vals = itertools::izip!(&clean_vals, &ids)
.map(|(dense, id)| {
let mut next = 0;
let mut grow = make_growable(&[dense.as_ref()], true, self.len());
typed_arr.types().iter().for_each(|t| {
if *t == *id as i8 {
grow.extend(0, next, 1);
next += 1;
} else {
grow.extend_validity(1);
}
});
grow.as_box()
})
.collect_vec();
let clean_field_types = itertools::izip!(fields, &clean_vals)
.map(|(f, v)| Field::new(&f.name, v.data_type().clone(), f.is_nullable))
.collect_vec();
// The new type will be a struct
let clean_data = DataType::Struct(clean_field_types);
StructArray::try_new(clean_data, padded_vals, typed_arr.validity().cloned())
.unwrap()
.boxed()
}
DataType::Union(fields, ids, UnionMode::Sparse) => {
// Recursively clean the contents and convert `UnionArray` -> `StructArray`
let typed_arr = self.as_any().downcast_ref::<UnionArray>().unwrap();
// Note: Union calls its stored value-arrays "fields"
let clean_vals = typed_arr
.fields()
.iter()
.map(|v| v.as_ref().clean_for_polars())
.collect_vec();
let ids = ids
.clone()
.unwrap_or_else(|| (0i32..(clean_vals.len() as i32)).collect_vec());
// For Sparse Unions, the value-arrays is already the right
// correct length, but should have a validity derived from the types array.
let padded_vals = itertools::izip!(&clean_vals, &ids)
.map(|(sparse, id)| {
let validity = Bitmap::from(
typed_arr
.types()
.iter()
.map(|t| *t == *id as i8)
.collect_vec(),
);
sparse.with_validity(Some(validity))
})
.collect_vec();
let clean_field_types = itertools::izip!(fields, &clean_vals)
.map(|(f, v)| Field::new(&f.name, v.data_type().clone(), f.is_nullable))
.collect_vec();
// The new type will be a struct
let clean_data = DataType::Struct(clean_field_types);
StructArray::try_new(clean_data, padded_vals, typed_arr.validity().cloned())
.unwrap()
.boxed()
}
_ => self.to_boxed(),
}
}
}
#[test]
fn test_clean_for_polars_nomodify() {
use re_log_types::datagen::build_some_colors;
use re_log_types::DataCell;
// Colors don't need polars cleaning
let cell: DataCell = build_some_colors(5).try_into().unwrap();
let cleaned = cell.as_arrow_ref().clean_for_polars();
assert_eq!(cell.as_arrow_ref(), &*cleaned);
}
#[cfg(test)]
mod tests {
use arrow2::datatypes::{DataType, Field, UnionMode};
use arrow2_convert::{ArrowDeserialize, ArrowField, ArrowSerialize};
use re_log_types::{component_types::Vec3D, Component, DataCell};
use crate::ArrayExt;
#[derive(Clone, Copy, Debug, PartialEq, ArrowField, ArrowSerialize, ArrowDeserialize)]
#[arrow_field(type = "dense")]
enum TestComponentWithUnionAndFixedSizeList {
Bool(bool),
Vec3D(Vec3D),
}
impl Component for TestComponentWithUnionAndFixedSizeList {
fn name() -> re_log_types::ComponentName {
"test_component_with_union_and_fixed_size_list".into()
}
}
#[test]
fn test_clean_for_polars_modify() {
// Pick a type with both Unions and FixedSizeLists
let elements = vec![TestComponentWithUnionAndFixedSizeList::Bool(false)];
let cell: DataCell = elements.try_into().unwrap();
assert_eq!(
*cell.datatype(),
DataType::Union(
vec![
Field::new("Bool", DataType::Boolean, false),
Field::new(
"Vec3D",
DataType::FixedSizeList(
Box::new(Field::new("item", DataType::Float32, false)),
3
),
false
)
],
None,
UnionMode::Dense
)
);
let cleaned = cell.as_arrow_ref().clean_for_polars();
assert_eq!(
*cleaned.data_type(),
DataType::Struct(vec![
Field::new("Bool", DataType::Boolean, false),
Field::new(
"Vec3D",
DataType::List(Box::new(Field::new("item", DataType::Float32, false))),
false
)
],)
);
}
}