Declarative classes¶
In this section a series of classes that are meant to declare datatypes that are required for creating primary PyTables datasets are described.
The Atom class and its descendants¶
Atom properties¶
Atom methods¶
Atom factory methods¶
Atom Sub-classes¶
Pseudo atoms¶
Now, there come three special classes, ObjectAtom, VLStringAtom and VLUnicodeAtom, that actually do not descend from Atom, but which goal is so similar that they should be described here. Pseudo-atoms can only be used with VLArray datasets (see The VLArray class), and they do not support multidimensional values, nor multiple values per row.
They can be recognised because they also have kind, type and shape attributes, but no size, itemsize or dflt ones. Instead, they have a base atom which defines the elements used for storage.
See examples/vlarray1.py and examples/vlarray2.py for further
examples on VLArray datasets, including object serialization and string
management.
ObjectAtom¶
VLStringAtom¶
VLUnicodeAtom¶
The Col class and its descendants¶
Col instance variables¶
In addition to the variables that they inherit from the Atom class, Col instances have the following attributes.
-
Col._v_pos¶ The relative position of this column with regard to its column siblings.
