Struct CastColumnsPolicy 

pub struct CastColumnsPolicy {
    pub integer_upcast: bool,
    pub float_upcast: bool,
    pub float_downcast: bool,
    pub datetime_nanoseconds_downcast: bool,
    pub datetime_microseconds_downcast: bool,
    pub datetime_convert_timezone: bool,
    pub null_upcast: bool,
    pub categorical_to_string: bool,
    pub missing_struct_fields: MissingColumnsPolicy,
    pub extra_struct_fields: ExtraColumnsPolicy,
}

Available on crate feature lazy only.

Used by scans.

Fields

integer_upcast: bool

Allow casting when target dtype is lossless supertype

float_upcast: bool

Allow Float32 -> Float64

float_downcast: bool

Allow Float64 -> Float32

datetime_nanoseconds_downcast: bool

Allow datetime[ns] to be casted to any lower precision. Important for being able to read datasets written by spark.

datetime_microseconds_downcast: bool

Allow datetime[us] to datetime[ms]

datetime_convert_timezone: bool

Allow casting to change time units.

null_upcast: bool

DataType::Null to any

categorical_to_string: bool

DataType::Categorical to string

missing_struct_fields: MissingColumnsPolicy

extra_struct_fields: ExtraColumnsPolicy

Implementations

impl CastColumnsPolicy

pub const ERROR_ON_MISMATCH: CastColumnsPolicy

Configuration variant that defaults to raising on mismatch.

impl CastColumnsPolicy

pub fn should_cast_column( &self, column_name: &str, target_dtype: &DataType, incoming_dtype: &DataType, ) -> Result<bool, PolarsError>

Checks if casting can be done to a dtype with a configured policy.

Returns

• Ok(true): Cast needed to target dtype
• Ok(false): No casting needed
• Err(_): Forbidden by configuration, or incompatible types.

Trait Implementations

impl Clone for CastColumnsPolicy

fn clone(&self) -> CastColumnsPolicy

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CastColumnsPolicy

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for CastColumnsPolicy

fn default() -> CastColumnsPolicy

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for CastColumnsPolicy

fn deserialize<__D>( __deserializer: __D, ) -> Result<CastColumnsPolicy, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for CastColumnsPolicy

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for CastColumnsPolicy

fn eq(&self, other: &CastColumnsPolicy) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for CastColumnsPolicy

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for CastColumnsPolicy

impl StructuralPartialEq for CastColumnsPolicy