Method new_from_strings

arrow-array/src/array/map_array.rs:327–362

Creates map array from provided keys, values and entry_offsets.

(
        keys: impl Iterator<Item = &'a str>,
        values: &dyn Array,
        entry_offsets: &[u32],
    )

    /// Creates map array from provided keys, values and entry_offsets.
    pub fn new_from_strings<'a>(
        keys: impl Iterator<Item = &'a str>,
        values: &dyn Array,
        entry_offsets: &[u32],
    ) -> Result<Self, ArrowError> {
        let entry_offsets_buffer = Buffer::from(entry_offsets.to_byte_slice());
        let keys_data = StringArray::from_iter_values(keys);

        let keys_field = Arc::new(Field::new("keys", DataType::Utf8, false));
        let values_field = Arc::new(Field::new(
            "values",
            values.data_type().clone(),
            values.null_count() > 0,
        ));

        let entry_struct = StructArray::from(vec![
            (keys_field, Arc::new(keys_data) as ArrayRef),
            (values_field, make_array(values.to_data())),
        ]);

        let map_data_type = DataType::Map(
            Arc::new(Field::new(
                "entries",
                entry_struct.data_type().clone(),
                false,
            )),
            false,
        );
        let map_data = ArrayData::builder(map_data_type)
            .len(entry_offsets.len() - 1)
            .add_buffer(entry_offsets_buffer)
            .add_child_data(entry_struct.into_data())
            .build()?;

        Ok(MapArray::from(map_data))
    }
}

/// SAFETY: Correctly implements the contract of Arrow Arrays