pyarrow.dataset.Expression

class pyarrow.dataset.Expression

Bases: pyarrow.lib._Weakrefable

A logical expression to be evaluated against some input.

To create an expression:

• Use the factory function pyarrow.dataset.scalar() to create a scalar (not necessary when combined, see example below).

• Use the factory function pyarrow.dataset.field() to reference a field (column in table).

• Compare fields and scalars with <, <=, ==, >=, >.

• Combine expressions using python operators & (logical and), | (logical or) and ~ (logical not). Note: python keywords and, or and not cannot be used to combine expressions.

• Check whether the expression is contained in a list of values with the pyarrow.dataset.Expression.isin() member function.

Examples

>>> import pyarrow.dataset as ds
>>> (ds.field("a") < ds.scalar(3)) | (ds.field("b") > 7)
<pyarrow.dataset.Expression ((a < 3:int64) or (b > 7:int64))>
>>> ds.field('a') != 3
<pyarrow.dataset.Expression (a != 3)>
>>> ds.field('a').isin([1, 2, 3])
<pyarrow.dataset.Expression (a is in [
  1,
  2,
  3
])>

__init__(*args, **kwargs)

Initialize self. See help(type(self)) for accurate signature.

Methods

__init__(*args, **kwargs)	Initialize self.
cast	Explicitly change the expression’s data type
equals
is_null	Checks whether the expression is null
is_valid	Checks whether the expression is not-null (valid)
isin	Checks whether the expression is contained in values

cast()

Explicitly change the expression’s data type

equals()

is_null()

Checks whether the expression is null

is_valid()

Checks whether the expression is not-null (valid)

isin()

Checks whether the expression is contained in values

pyarrow.dataset.Scanner Plasma In-Memory Object Store