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Vectors

A Vector is an Array-like data structure. Use makeVector and vectorFromArray to create vectors.

makeVector​

vectorFromArray​

Vector​

Also referred to as BaseVector. An abstract base class for vector types.

  • Can support a null map
  • ...
  • TBD

Fields​

type: DataType​

The Arrow DataType that describes the elements in this Vector.

data: Data<T> (readonly)​

The underlying Data instance for this Vector.

numChildren: number (readonly)​

The number of logical Vector children. Only applicable if the DataType of the Vector is one of the nested types (List, FixedSizeList, Struct, or Map).

typeId: T['typeId']​

The typeId enum value of the type instance

length: number​

Number of elements in the Vector

offset: number​

Offset to the first element in the underlying data.

stride: number​

Stride between successive elements in the the underlying data.

The number of elements in the underlying data buffer that constitute a single logical value for the given type. The stride for all DataTypes is 1 unless noted here:

  • For Decimal types, the stride is 4.
  • For Date types, the stride is 1 if the unit is DateUnit.DAY, else 2.
  • For Int, Interval, or Time types, the stride is 1 if bitWidth <= 32, else 2.
  • For FixedSizeList types, the stride is the listSize property of the FixedSizeList instance.
  • For FixedSizeBinary types, the stride is the byteWidth property of the FixedSizeBinary instance.

nullCount: number​

Number of null values in this Vector instance (null values require a null map to be present).

VectorName: string​

Returns the name of the Vector

ArrayType: TypedArrayConstructor | ArrayConstructor​

Returns the constructor of the underlying typed array for the values buffer as determined by this Vector's DataType.

values: T['TArray']​

Returns the underlying data buffer of the Vector, if applicable.

typeIds: Int8Array | null​

Returns the underlying typeIds buffer, if the Vector DataType is Union.

nullBitmap: Uint8Array | null​

Returns the underlying validity bitmap buffer, if applicable.

Note: Since the validity bitmap is a Uint8Array of bits, it is not sliced when you call vector.slice(). Instead, the vector.offset property is updated on the returned Vector. Therefore, you must factor vector.offset into the bit position if you wish to slice or read the null positions manually. See the implementation of BaseVector.isValid() for an example of how this is done.

valueOffsets: Int32Array | null​

Returns the underlying valueOffsets buffer, if applicable. Only the List, Utf8, Binary, and DenseUnion DataTypes will have valueOffsets.

Methods​

clone(data: Data<R>, children): Vector<R>​

Returns a clone of the current Vector, using the supplied Data and optional children for the new clone. Does not copy any underlying buffers.

concat(...others: Vector<T>[])​

Returns a Chunked vector that concatenates this Vector with the supplied other Vectors. Other Vectors must be the same type as this Vector.

slice(begin?: number, end?: number)​

Returns a zero-copy slice of this Vector. The begin and end arguments are handled the same way as JS' Array.prototype.slice; they are clamped between 0 and vector.length and wrap around when negative, e.g. slice(-1, 5) or slice(5, -1)

isValid()​

vector.isValid(index: number): boolean

Returns true the supplied index is valid in the underlying validity bitmap.

getChildAt()​

vector.getChildAt<R extends DataType = any>(index: number): Vector<R> | null

Returns the inner Vector child if the DataType is one of the nested types such as Map or Struct.

toJSON()​

Returns a dense JS Array of the Vector values, with null sentinels in-place.