Function cast

pub fn cast(
    array: &dyn Array,
    to_type: &ArrowDataType,
    options: CastOptionsImpl,
) -> PolarsResult<Box<dyn Array>>

Available on crate feature compute_cast only.

Cast array to the provided data type and return a new Array with type to_type, if possible.

Behavior:

• PrimitiveArray to PrimitiveArray: overflowing cast will be None
• Boolean to Utf8: true => ‘1’, false => 0
• Utf8 to numeric: strings that can’t be parsed to numbers return null, float strings in integer casts return null
• Numeric to boolean: 0 returns false, any other value returns true
• List to List: the underlying data type is cast
• Fixed Size List to List: the underlying data type is cast
• List to Fixed Size List: the offsets are checked for valid order, then the underlying type is cast.
• Struct to Struct: the underlying fields are cast.
• PrimitiveArray to List: a list array with 1 value per slot is created
• Date32 and Date64: precision lost when going to higher interval
• Time32 and Time64: precision lost when going to higher interval
• Timestamp and Date{32|64}: precision lost when going to higher interval
• Temporal to/from backing primitive: zero-copy with data type change

Unsupported Casts

• non-StructArray to StructArray or StructArray to non-StructArray
• List to primitive
• Utf8 to boolean
• Interval and duration