在 Python 中生成具有平行标记边/顶点的有向图

Question

What is the best way to generate a Directed Graph With Parallel Labelled Edges/Vertices in Python like the one in the Image below??

I have already tried networkx but it does not work with parallel edges.

This is the code I'm using to generate the data for the Graph.

from forex_python.converter import CurrencyRates
import pandas as pd

chosen_currencies = ['GBP', 'EUR', 'USD']

c = CurrencyRates()

rates = []


for currency_index in range(len(chosen_currencies)):
    temp_list = []
    for second_index in range(len(chosen_currencies)):
        temp_list.append(c.get_rate(chosen_currencies[currency_index], chosen_currencies[second_index]))
    rates.append(temp_list)

df = (pd.DataFrame.from_records(rates)).transpose()
df.columns = chosen_currencies

Answer 1

You can use the dataframe to read the edges directly into a NetworkX graph using from_pandas_adjacency . In order to do that, lets set the index of the dataframe equal to chosen_currencies , to ensure that the edges are mapped correctly.

from forex_python.converter import CurrencyRates
import pandas as pd

chosen_currencies = ['GBP', 'EUR', 'USD']

c = CurrencyRates()

rates = []


for currency_index in range(len(chosen_currencies)):
    temp_list = []
    for second_index in range(len(chosen_currencies)):
        temp_list.append(c.get_rate(chosen_currencies[currency_index], chosen_currencies[second_index]))
    rates.append(temp_list)

df = (pd.DataFrame.from_records(rates)).transpose()
df.columns = chosen_currencies
#   GBP         EUR     USD
#0  1.000000    0.83238 0.768233
#1  1.201374    1.00000 0.922935
#2  1.301689    1.08350 1.000000

Now set the index

df.set_index([pd.Index(chosen_currencies)], inplace=True)
#       GBP         EUR     USD
#GBP    1.000000    0.83238 0.768233
#EUR    1.201374    1.00000 0.922935
#USD    1.301689    1.08350 1.000000

Now let's create the graph

import networkx as nx
import matplotlib.pyplot as plt

G = nx.from_pandas_adjacency(df, create_using=nx.DiGraph)

# Set the figure size
plt.figure(figsize=(8,8))

# Get the edge labels and round them to 3 decimal places
# for more clarity while drawing
edge_labels = dict([((u,v), round(d['weight'], 3))
             for u,v,d in G.edges(data=True)])

# Get the layout
pos = nx.spring_layout(G)

# Draw edge labels and graph
nx.draw_networkx_edge_labels(G,pos,edge_labels=edge_labels,
                             label_pos=0.15, font_size=10)
nx.draw(G, pos, with_labels=True,
        connectionstyle='arc3, rad = 0.15',
        node_size=800)

plt.show()

Note: The number near the arrowhead is the edge weight.

You can also view this Google Colab Notebook with above working example.

You can adjust the font size, label position, etc. according to your requirements.

References:

• Connection Style
• Draw Edge Labels
• Drawing multiple edge labels