Class Group

tables/group.py:39–1132

Basic PyTables grouping structure. Instances of this class are grouping structures containing *child* instances of zero or more groups or leaves, together with supporting metadata. Each group has exactly one *parent* group. Working with groups and leaves is similar in many ways to

class Group(hdf5extension.Group, Node):
    """Basic PyTables grouping structure.

    Instances of this class are grouping structures containing *child*
    instances of zero or more groups or leaves, together with
    supporting metadata. Each group has exactly one *parent* group.

    Working with groups and leaves is similar in many ways to working
    with directories and files, respectively, in a Unix filesystem.
    As with Unix directories and files, objects in the object tree are
    often described by giving their full (or absolute) path names.
    This full path can be specified either as a string (like in
    '/group1/group2') or as a complete object path written in *natural
    naming* schema (like in file.root.group1.group2).

    A collateral effect of the *natural naming* schema is that the
    names of members in the Group class and its instances must be
    carefully chosen to avoid colliding with existing children node
    names.  For this reason and to avoid polluting the children
    namespace all members in a Group start with some reserved prefix,
    like _f_ (for public methods), _g_ (for private ones), _v_ (for
    instance variables) or _c_ (for class variables). Any attempt to
    create a new child node whose name starts with one of these
    prefixes will raise a ValueError exception.

    Another effect of natural naming is that children named after
    Python keywords or having names not valid as Python identifiers
    (e.g.  class, $a or 44) can not be accessed using the node.child
    syntax. You will be forced to use node._f_get_child(child) to
    access them (which is recommended for programmatic accesses).

    You will also need to use _f_get_child() to access an existing
    child node if you set a Python attribute in the Group with the
    same name as that node (you will get a NaturalNameWarning when
    doing this).

    Parameters
    ----------
    parentnode
        The parent :class:`Group` object.
    name : str
        The name of this node in its parent group.
    title
        The title for this group
    new
        If this group is new or has to be read from disk
    filters : Filters
        A Filters instance


    .. versionchanged:: 3.0
       *parentNode* renamed into *parentnode*

    Notes
    -----
    The following documentation includes methods that are automatically
    called when a Group instance is accessed in a special way.