Networkx: Replacing labels of nodes

Question

I have the following minimal code:

import networkx as nx
import matplotlib.pyplot as plt

G = nx.DiGraph()
#G = nx.Graph()
#G = nx.path_graph(4)

pos1 = {0: (0, 0), 1: (2, 1), 2: (2, 0), 3: (2,-1)}
G.add_edge(0, 1)
G.add_edge(0, 3)
G.add_edge(1, 2)
G.add_edge(2, 3)

# First Network
plt.figure(0)
nx.draw_networkx(G, pos1) # Puts numbers as labels of nodes
plt.axis("off")
plt.savefig('graph1.png')

# Second network 
plt.figure(1)
mapping = {0: "Zero", 1: "One", 2: "Two", 3: "Three"}
H = nx.relabel_nodes(G, mapping)
nx.draw_networkx(H)  # Works

''' The below line I want to modify '''
#nx.draw_networkx(H, pos1) # Doesn't work  
                          # Says: NetworkXError: Node 'Zero' has no position 

plt.axis("off")
plt.savefig('graph2.png')
plt.show() 

Here I am trying to replace the label names in the new graph H . But it shows an error since I am using coordinates for the nodes.

Right now the outputs are:

The second graph needs to be corrected. Also, can the sizes of the nodes be auto-adjusted and even-odd numbered (labels for the first.network) nodes be colored differently?

PS. If networkx has limitations, then an example with some other module may also serve the purpose.

Answer 1

The simplest approach would be to create a relabelled pos dictionary using the new node names:

pos1 = {0: (0, 0), 1: (2, 1), 2: (2, 0), 3: (2,-1)}
mapping = {0: "Zero", 1: "One", 2: "Two", 3: "Three"}
pos_new = {mapping[k]: v for k, v in pos1.items()}
# use the above with nx.draw_networkx(H, pos_new)

Answer 2

I think the best way to solve this is to not use the nx.draw.networkx command but rather the separate draw commands for labels, nodes and edges. With nx.draw.networkx_labels you can pass your dictionary directly without changing your nodes names:

import networkx as nx
import matplotlib.pyplot as plt

G = nx.DiGraph()

pos1 = {0: (0, 0), 1: (2, 1), 2: (2, 0), 3: (2,-1)}
G.add_edge(0, 1)
G.add_edge(0, 3)
G.add_edge(1, 2)
G.add_edge(2, 3)

node_colors = ['red'if i%2==0 else 'blue' for i in G.nodes]
mapping = {0: "Zero", 1: "One", 2: "Two", 3: "Three"}

plt.figure()

nx.draw_networkx_nodes(G, pos=pos1,node_color=node_colors, node_size=500)
nx.draw_networkx_edges(G, pos=pos1)
nx.draw_networkx_labels(G, pos=pos1, labels=mapping)

plt.axis("off")
plt.show() 

This produces:

If you want to fit the node sizes to the labels, manipulate them. If you only care about the text, not about the node itself. Don't use the nx.draw.networkx_nodes command, instead add the bbox argument to nx.draw.networkx_labels . Like so:

plt.figure()

#nx.draw_networkx_nodes(G, pos=pos1,node_color=node_colors, node_size=500)
nx.draw_networkx_edges(G, pos=pos1)
nx.draw_networkx_labels(G, pos=pos1, labels=mapping, bbox ={})

plt.axis("off")
plt.show() 

Which produces: