Data preprocessing¶

Convert and replace the data in a table. These methods are available on pykx.Table and pykx.KeyedTable objects.

astype ¶

astype(dtype, copy=True, errors='raise')

Cast columns of the table to a different data type.

Parameters:

Name	Type	Description	Default
`dtype`	`type or dict`	A `pykx` or Python type to cast every column to, or a dictionary of column names to types.	required
`copy`	`bool`	Only `True` is implemented.	`True`
`errors`	`str`	`'raise'` raises an error if a cast fails. Any other value returns the table unchanged.	`'raise'`

Returns:

Type	Description
`Table`	The table with the columns cast.

Examples:

>>> tab = kx.q('([] a:1 2 3; b:4 5 6)')
>>> tab.astype(kx.FloatVector)
pykx.Table(pykx.q('
a b
---
1 4
2 5
3 6
'))

select_dtypes ¶

select_dtypes(include=None, exclude=None)

Select the columns of the table by their data types.

At least one of include and exclude is required and they cannot overlap. If both are given exclude is ignored. For a KeyedTable the key columns are always kept and only the value columns are filtered. Use kx.CharAtom for a column of single characters, as kx.CharVector raises an error.

Parameters:

Name	Type	Description	Default
`include`	`type, str or list`	A data type or string, or a list of them, of the columns to keep.	`None`
`exclude`	`type, str or list`	A data type or string, or a list of them, of the columns to remove.	`None`

Returns:

Type	Description
`Table`	The table of the selected columns, or `pykx.Identity(pykx.q("::"))` if there are none.

Examples:

>>> tab = kx.q('([] a:1 2 3; b:1.5 2.5 3.5)')
>>> tab.select_dtypes(include=kx.FloatVector)
pykx.Table(pykx.q('
b
---
1.5
2.5
3.5
'))

replace ¶

replace(to_replace, value)

Replace all occurrences of a value in the table.

Parameters:

Name	Type	Description	Default
`to_replace`	`Any`	The value to replace.	required
`value`	`Any`	The value to replace it with.	required

Returns:

Type	Description
`Table`	The table with the values replaced.

Examples:

>>> tab = kx.q('([] a:1 2 3; b:4 5 6)')
>>> tab.replace(5, 50)
pykx.Table(pykx.q('
a b
----
1 4
2 50
3 6
'))