NodeView.data#

NodeView.data(data=True, default=None)[source]#

Return a read-only view of node data.

Parameters:

databool or node data key, default=True: If data=True (the default), return a NodeDataView object that maps each node to all of its attributes. data may also be an arbitrary key, in which case the NodeDataView maps each node to the value for the keyed attribute. In this case, if a node does not have the data attribute, the default value is used.
defaultobject, default=None: The value used when a node does not have a specific attribute.

Returns:

NodeDataView: The layout of the returned NodeDataView depends on the value of the data parameter.

See also

NodeDataView

Notes

If data=False, returns a NodeView object without data.

Examples

>>> G = nx.Graph()
>>> G.add_nodes_from(
...     [
...         (0, {"color": "red", "weight": 10}),
...         (1, {"color": "blue"}),
...         (2, {"color": "yellow", "weight": 2}),
...     ]
... )

Accessing node data with data=True (the default) returns a NodeDataView mapping each node to all of its attributes:

>>> G.nodes.data()
NodeDataView({0: {'color': 'red', 'weight': 10}, 1: {'color': 'blue'}, 2: {'color': 'yellow', 'weight': 2}})

If data represents a key in the node attribute dict, a NodeDataView mapping the nodes to the value for that specific key is returned:

>>> G.nodes.data("color")
NodeDataView({0: 'red', 1: 'blue', 2: 'yellow'}, data='color')

If a specific key is not found in an attribute dict, the value specified by default is returned:

>>> G.nodes.data("weight", default=-999)
NodeDataView({0: 10, 1: -999, 2: 2}, data='weight')

Note that there is no check that the data key is in any of the node attribute dictionaries:

>>> G.nodes.data("height")
NodeDataView({0: None, 1: None, 2: None}, data='height')