Color a particular node in Networkx and Graphviz
Question: I am writing a program to plot a graph from a distance matrix. It is working
fine. Now I want a certain node and a certain edge to be of a particular color
of my choice. How do I do that?

The program is in Python and uses Networkx and Graphviz

    
    
    import networkx as nx
    import numpy as np
    import pickle
    from random import randint
    
    p_file = open('pickles/distance')
    Dist = pickle.load(p_file)
    p_file.close()
    p_file = open('pickles/names')
    Names = pickle.load(p_file)
    p_file.close()
    
    dt = [('len', float)]
    A = np.array(Dist)*5
    A = A.view(dt)
    
    G = nx.from_numpy_matrix(A)
    G = nx.relabel_nodes(G, dict(zip(range(len(G.nodes())),Names)))    
    
    G = nx.to_agraph(G)
    G.node_attr.update(ndcolor="red", node="DC", style="filled")
    G.edge_attr.update(color="none")
    G.draw('P1.png', format='png', prog='neato')
    


Answer: Since you are using Graphviz to do the drawing you need to use the attributes
that Graphviz understands. See <http://www.graphviz.org/content/attrs>

    
    
    import networkx as nx
    G = nx.Graph()
    
    G.add_node(1,color='red',style='filled',fillcolor='blue',shape='square')
    G.add_node(2,color='blue',style='filled')
    G.add_edge(1,2,color='green')
    G.node[2]['shape']='circle'
    G.node[2]['fillcolor']='red'
    
    A = nx.to_agraph(G)
    A.layout()
    A.draw('color.png')
    print A.to_string()
    

Gives

    
    
    strict graph {
        graph [bb="0,0,107.21,46.639"];
        node [label="\N"];
        1    [color=red,
            fillcolor=blue,
            height=0.5,
            pos="18,28.639",
            shape=square,
            style=filled,
            width=0.5];
        2    [color=blue,
            fillcolor=red,
            height=0.5,
            pos="89.21,18",
            shape=circle,
            style=filled,
            width=0.5];
        1 -- 2   [color=green,
            pos="36.338,25.899 47.053,24.298 60.519,22.286 71.18,20.694"];
    }
    

![enter image description here](http://i.stack.imgur.com/lcUfo.png)

