How to add labels to nodes in a graph in networkx?

Question

I am writing a code for integer partition and constructing a graph where each node is a partition. I would like to label the nodes in the graph with partition elements like {2,1,1}, {1,1,1,1},{2,2} etc.

So I want to know, how to label a node in networkx.

I have already seen the code for labeling node but I didn't get it. The code is given below:

nx.draw_networkx_nodes(G,pos,
                       nodelist=[0,1,2,3],
                       node_color='r',
                       node_size=500,
                    alpha=0.8)

But what I want is to label individual nodes of already constructed graph!

I am providing my code here, so that you can have better understanding of it.

import networkx as nx
from matplotlib import pylab as pl

def partitions(num):
    final=[[num]]

    for i in range(1,num):
        a=num-i
        res=partitions(i)
        for ele in res:
            if ele[0]<=a:
                final.append([a]+ele)

    return final

def drawgraph(parlist):
    #This is to draw the graph
    G=nx.Graph()
    length=len(parlist)
    print "length is %s\n" % length

    node_list=[]

    for i in range(1,length+1):
        node_list.append(i)

    G.add_cycle(node_list)

    nx.draw_circular(G)
    pl.show()

Please help me.

Thank you very much

Answer 1

Since your node_list was composed of integers, your nodes got the string representation of those integers as labels. But your nodes can be any hashable object, not just integers. So the simplest thing to do would be to make your node_list the string representation of the items in parlist. (The items in parlist are lists, which are mutable and therefore not hashable. That's why we can't just use parlist as our node_list.)

There is also the function nx.relabel_nodes, which we could use instead, but I think just giving the nodes the right label in the first place is simpler.

import networkx as nx
import matplotlib.pyplot as plt


def partitions(num):
    final = [[num]]

    for i in range(1, num):
        a = num - i
        res = partitions(i)
        for ele in res:
            if ele[0] <= a:
                final.append([a] + ele)

    return final


def drawgraph(parlist):
    G = nx.Graph()
    length = len(parlist)
    print "length is %s\n" % length
    node_list = [str(item) for item in parlist]
    G.add_cycle(node_list)
    pos = nx.circular_layout(G)
    draw_lifted(G, pos)


def draw_lifted(G, pos=None, offset=0.07, fontsize=16):
    """Draw with lifted labels
    http://networkx.lanl.gov/examples/advanced/heavy_metal_umlaut.html
    """
    pos = nx.spring_layout(G) if pos is None else pos
    nx.draw(G, pos, font_size=fontsize, with_labels=False)
    for p in pos:  # raise text positions
        pos[p][1] += offset
    nx.draw_networkx_labels(G, pos)
    plt.show()

drawgraph(partitions(4))

yields