Expressions¶

Vortex expressions represent simple filtering conditions on the rows of a Vortex array. For example, the following expression represents the set of rows for which the age column lies between 23 and 55:

>>> import vortex.expr
>>> age = vortex.expr.column("age")
>>> (23 > age) & (age < 55)

`column`	Create an expression that refers to a column by its name.
`Expr`	An expression describes how to filter rows when reading an array from a file.

vortex.expr.column(name)¶

Create an expression that refers to a column by its name.

Parameters:: name (str) – The name of the column.
Return type:: vortex.Expr

Examples

>>> import vortex.expr as ve
>>> ve.column("age")
<vortex.Expr object at ...>

vortex.expr.not_(child)¶

Negate a Boolean expression.

Parameters:: child (Any) – A boolean expression.
Return type:: vortex.Expr

Examples

>>> import vortex.expr as ve
>>> import vortex as vx
>>> ve.not_(ve.literal(vx.int_(), 42) == ve.literal(vx.int_(), 42))
<vortex.Expr object at ...>

vortex.expr.and_(left, right)¶

True if both arguments are true.

Parameters:: child (Any) – A boolean expression.
Return type:: vortex.Expr

Examples

>>> import vortex.expr as ve
>>> import vortex as vx
>>> ve.and_(ve.literal(vx.bool_(), True), ve.literal(vx.bool_(), True))
<vortex.Expr object at ...>

vortex.expr.root()¶

Create an expression that refers to the identity scope.

That is, it returns the full input that the extension is run against.

Return type:: vortex.Expr

Examples

>>> import vortex.expr as ve
>>> ve.root()
<vortex.Expr object at ...>

vortex.expr.literal(dtype, value)¶

Create an expression that represents a literal value.

Parameters:

dtype (vortex.DType) – The data type of the literal value.
value (Any) – The literal value.

Return type:

vortex.Expr

Examples

>>> import vortex.expr as ve
>>> ve.literal(vx.int_(), 42)
<vortex.Expr object at ...>

class vortex.expr.Expr¶: An expression describes how to filter rows when reading an array from a file.

See also

column()