Reference¶

Rendering¶

nxv.render(graph, style=None, *, algorithm=None, format=None, graphviz_bin=None, subgraph_func=None)¶

Render a NetworkX graph using GraphViz.

In a Jupyter notebook, this will automatically display as an SVG.

Parameters

graph (Union[Graph, DiGraph, MultiGraph, MultiDiGraph]) – A NetworkX graph.
style (Optional[Style]) – A style specifying how graph nodes and edges should map to GraphViz attributes.
subgraph_func – An optional function f(u, d) that returns a subgraph key, where u is a NetworkX node and d is its attribute dict. If it returns None the node is not in any subgraph.
algorithm (Optional[str]) – The GraphViz layout algorithm. Valid options include "circo", "dot", "fdp", "neato", "osage", "sfdp", "twopi". Defaults to "dot".
format (Optional[str]) – The GraphViz output format. Valid options include "svg" and "raw". In a Jupyter notebook, prefixing the format with "ipython/" will automatically display the rendered output. When running in an interactive setting like a Jupyter notebook, the default is "ipython/svg". Otherwise, this parameter is required.
graphviz_bin (Optional[str]) – The bin directory of the GraphViz installation. Defaults to the GRAPHVIZ_BIN environment variable. If neither this parameter nor the GRAPHVIZ_BIN environment variable is set, then nxv will try to autodetect the bin directory of the GraphViz installation. This behavior is for convenience and should not be relied on in production settings.

Return type

Optional[bytes]

Returns

If format is not an "ipython/*" format, the render output; otherwise, None.

Raises

GraphVizInstallationNotFoundError – If nxv cannot find a GraphViz installation.
GraphVizAlgorithmNotFoundError – If nxv cannot find the specified algorithm in a GraphViz installation.
GraphVizError – If GraphViz failed to run on the given inputs.

Styling¶

class nxv.Style(*, graph=None, node=None, edge=None, subgraph=None)¶

A specification for how to style a NetworkX graph using GraphViz.

See the GraphViz attributes documentation for information on what attributes are available to use with the graph, node, edge, and subgraph parameters.

Parameters

graph – An optional dict of GraphViz graph attributes, or a function f(g, d) that returns it, in which g is the NetworkX graph and d is its attribute dict.
node – An optional dict of GraphViz node attributes, or a function f(u, d) that returns it, in which u is a NetworkX node and d is its attribute dict.
edge – An optional dict of GraphViz edge attributes, or a function f(u, v, d) that returns it, in which (u, v) is a NetworkX edge and d is its attribute dict. If styling a graph with multi-edges, the signature should be f(u, v, k, d) instead, where k is the edge key.
subgraph – An optional dict of GraphViz subgraph attributes, or a function f(s) that returns it, in which s is a subgraph key. This only applies when calling nxv.render with a subgraph_func.

nxv.compose(styles)¶

Compose a sequence of Style objects as a single Style.

Parameters: styles (Iterable[Optional[Style]]) – An iterable of Style objects.
Return type: Style
Returns: The composed Style.

nxv.chain(funcs)¶

Chain a sequence of dict-returning functions together to form a new dict-returning function.

The result is a function f(*args, **kwargs) that returns {**apply(funcs[0], *args, **kwargs), **apply(funcs[1], *args, **kwargs), ...}.

Parameters: funcs – An iterable of functions that return dicts.
Returns: A function f(*args, **kwargs) that returns {**apply(funcs[0], *args, **kwargs), **apply(funcs[1], *args, **kwargs), ...}.

nxv.switch(key, funcs, *, default=None)¶

Combine a dict of keyed functions to form a new function.

The result is a function f(*args, **kwargs) that returns apply(funcs[key(*args, **kwargs)], *args, **kwargs).

If key(*args, **kwargs) is not in funcs but default is present, apply(default, *args, **kwargs) will be returned instead.

Parameters

key – The key selector function.
funcs – The mapping from keys to functions.
default – An optional default function for keys that do not appear in funcs.

Returns

The function f(*args, **kwargs) that returns apply(funcs[key(*args, **kwargs)], *args, **kwargs).

nxv.styles.verbose()¶

Get a verbose Style that shows all of the data in a graph.

Return type: Style
Returns: A verbose Style.

nxv.styles.font(fontname=None, fontsize=None)¶

Styles text in a graph using the given font.

Parameters

fontname (Optional[str]) – Optional font name.
fontsize (Union[int, float, None]) – Optional font size.

Return type

Style

Returns

A Style object that applies this font.

HTML-Like Labels¶

The nxv.html_like subpackage provides functions for building GraphViz HTML-like labels.

The idiomatic import for this subpackage is:

import nxv.html_like as H

nxv.html_like.join(children)¶

nxv.html_like.line_break(attributes=None)¶

nxv.html_like.font(content, attributes=None)¶

nxv.html_like.italic(content)¶

nxv.html_like.bold(content)¶

nxv.html_like.underline(content)¶

nxv.html_like.overline(content)¶

nxv.html_like.subscript(content)¶

nxv.html_like.superscript(content)¶

nxv.html_like.strikethrough(content)¶

nxv.html_like.table(rows, attributes=None)¶

nxv.html_like.table_row(cells)¶

nxv.html_like.horizontal_rule()¶

nxv.html_like.table_cell(content, attributes=None)¶

nxv.html_like.vertical_rule()¶

nxv.html_like.image(attributes=None)¶

Utilities¶

nxv.neighborhood(graph, nodes, *, radius=None, cost=None)¶

Get the subgraph in the neighborhood of the specified nodes.

This is useful for viewing a small portion of a large graph.

Parameters

graph – A graph.
nodes – An iterable of nodes.
radius – The size of the neighborhood.
cost – A function f(u, v) specifying the cost of traversing from u to v.

Returns

The neighborhood subgraph.

nxv.boundary(graph, subgraph)¶

Get the nodes in the subgraph that have neighbors in the graph but not in the subgraph.

This is useful for conditionally styling nodes at the boundary of a subgraph. For example:

boundary = nxv.boundary(graph, subgraph)
style = nxv.Style(node=lambda u, d: {
    'style': 'dashed' if u in boundary else 'solid',
})
nxv.render(subgraph, style)

Parameters

graph – A graph.
subgraph – A subgraph of the graph.

Returns

The nodes in the subgraph that have neighbors in the graph but not in the subgraph.

nxv.to_ordered_graph(graph, node_key=None, edge_key=None, attr_key=None)¶

Create an ordered copy of the specified graph, with nodes and edges ordered by the specified key functions.

Parameters

graph – The graph to order.
node_key – The node key function, node_key(u, d). Defaults to the identity function.
edge_key – The edge key function, edge_key(u, v, d). If the graph has multi-edges, the signature should be edge_key(u, v, k, d) instead, where k is the edge key. Defaults to the identity function.
attr_key – The attribute key function, attr_key(k, v). Defaults to the identity function.

Returns

A copy of the graph with the nodes and edges ordered by the specified key functions.

nxv.contrasting_color(channels, *, options=None)¶

Get a color that most contrasts with a specified color.

Parameters

channels – The RGB or RGBA color channels. Values should be in the range [0, 1].
options – The possible contrasting colors. Defaults to black and white.

Returns

The color option that most contrasts the input color.

Errors¶

class nxv.GraphVizInstallationNotFoundError¶: Raised when a GraphViz installation is not found.

class nxv.GraphVizAlgorithmNotFoundError¶: Raised when a GraphViz algorithm is not found.

class nxv.GraphVizError¶: Raised when a GraphViz run fails.