DataType

Namespace: Polars.CSharp

Represents a Polars data type. Wraps the underlying Rust DataType Handle and provides high-level metadata.

Properties & Indexers

Property	Type	Description
ArrayShape	uint[]	The shape of the array
ArrayWidth	ulong	If this is an Array type, returns the fixed width. Returns 0 if not an Array type.
Binary	DataType	-
Boolean	DataType	-
Categories	Categories	Return underlying Categories for categorical type, for other types returns null
Date	DataType	-
EnumCategories	FrozenCategories	Return underlying FrozenCategories for enum type, for other types returns null
Float16	DataType	-
Float32	DataType	-
Float64	DataType	-
InnerType	DataType	Return the inner type of list/array. Non-List/Array input will return null.
Int128	DataType	-
Int16	DataType	-
Int32	DataType	-
Int64	DataType	-
Int8	DataType	-
IsCategorical	bool	-
IsDecimal	bool	-
IsEnum	bool	-
IsExtension	bool	-
IsFloat	bool	-
IsInteger	bool	-
IsNested	bool	-
IsNumeric	bool	Returns true if the type is a numeric type.
IsSignedInteger	bool	-
IsTemporal	bool	-
IsUnsignedInteger	bool	-
Kind	DataTypeKind	Gets the high-level kind of this data type.
Null	DataType	-
Precision	int	Gets the decimal precision.
SameAsInput	DataType	-
Scale	int	Gets the decimal scale.
String	DataType	-
StructFields	IReadOnlyList<Field>	Gets the fields of a Struct type. Returns null if this DataType is not a Struct.
Time	DataType	-
TimeUnit	TimeUnit	Gets the time unit for Datetime and Duration types.
TimeZone	string	Gets the timezone string for Datetime type. Returns null if the datetime has no timezone (naive datetime).
TimeZoneInfo	TimeZoneInfo	Gets the timezone info for Datetime type. Returns null if the datetime has no timezone (naive datetime).
UInt128	DataType	-
UInt16	DataType	-
UInt32	DataType	-
UInt64	DataType	-
UInt8	DataType	-
Unknown	DataType	-

Constructors & Static Methods

Array

Create a Fixed-Size List (Array) data type.

Example: DataType.Array(DataType.Int32, 3),DataType.Array(typeof(int), 3)

public static DataType Array(DataType inner, params uint[] shape)

Parameters

Name	Type	Description
inner	DataType	The data type of the elements.
shape	uint[]	The shape of the arrays.

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Categorical

Create a Categorical type

public static DataType Categorical(Categories? categories = null)
public static DataType Categorical(string categories)

Parameters

Name	Type	Description
categories	Categories? / string	-

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Datetime

Create a datetime type with unit and timezone

public static DataType Datetime(TimeUnit unit = TimeUnit.Microseconds, string? timeZone = null)

Parameters

Name	Type	Description
unit	TimeUnit	precision (ns, us, ms)
timeZone	string?	timezone string (e.g. "Asia/Shanghai")， null for no timezone (Naive)

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Decimal

Create a Decimal type

public static DataType Decimal(int precision = 38, int scale = 9)

Parameters

Name	Type	Description
precision	int	-
scale	int	-

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Duration

Creates a Duration type. Default is Microseconds. Usage: DataType.Duration(TimeUnit.Nanoseconds)

public static DataType Duration(TimeUnit unit = TimeUnit.Microseconds)

Parameters

Name	Type	Description
unit	TimeUnit	-

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Enum

Create a Enum type

public static DataType Enum(FrozenCategories categories)
public static DataType Enum(Series categories)
public static DataType Enum(string[] categories)
public static DataType Enum(Categories categories)
public static DataType Enum<T>()

Parameters

Name	Type	Description
categories	FrozenCategories / Series / string[]	-

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Extension

Create an Extension data type

public static DataType Extension(string name, DataType inner, string? metadata = null)

Parameters

Name	Type	Description
name	string	The registered name of the extension type (e.g. "geoarrow.wkb")
inner	DataType	The physical storage data type
metadata	string?	Optional metadata string

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FromArrowType

Generate DataType from ArrowType

public static DataType FromArrowType(IArrowType arrowType)

Parameters

Name	Type	Description
arrowType	IArrowType	-

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FromNetType

Create a DataType from a .NET Type

public static DataType FromNetType<T>()

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List

Creates a List type. Usage: DataType.List(DataType.Int32)

public static DataType List(DataType innerType)

Parameters

Name	Type	Description
innerType	DataType	-

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Struct

Create Struct composite type.

public static DataType Struct(IEnumerable<Field> fields)
public static DataType Struct(params Field[] fields)
public static DataType Struct(IReadOnlyDictionary<string, DataType> fields)
public static DataType Struct(string[] names, DataType[] types)

Parameters

Name	Type	Description
fields	IEnumerable<Field> / Field[] / IReadOnlyDictionary<string, DataType>	Definition of a single field within a Struct DataType.
names	string[]	-
types	DataType[]	-

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Operators

operator == (Equality)

public static bool operator ==(DataType? left, DataType? right)

Parameters

Name	Type	Description
left	DataType?	-
right	DataType?	-

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implicit operator

Implicitly convert System.Type to Polars DataType. Example: DataType dt = typeof(int); // dt is now DataType.Int32

public static implicit operator DataType(Type type)

Parameters

Name	Type	Description
type	Type	-

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operator != (Inequality)

public static bool operator !=(DataType? left, DataType? right)

Parameters

Name	Type	Description
left	DataType?	-
right	DataType?	-

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Instance Methods

GetArrowType

Get Apache Arrow Type

public IArrowType GetArrowType()

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GetNetType

Get the .NET type corresponding to this DataType

public Type GetNetType()

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ToDataTypeExpr

Convert this DataType to a DataTypeExpr literal. Equivalent to Python's polars.DataType.to_dtype_expr()

public DataTypeExpr ToDataTypeExpr()

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