final_solution.py

import json
import numpy as np
import matplotlib.pyplot as plt


graph_data = json.loads(open("routes.json").read())

totals = {}
for start_country in graph_data:
    data = graph_data[start_country]
    # Get the sum of the number of routes to this country and store it
    totals[start_country] = sum(data["to"].values())
    

# From here we can use the same code we saw in Lesson 1 : http://saliksyed.com/index.php/getting-started-with-basic-data-visualization-charting/

# the categorical values (names)
countries = totals.iterkeys()

# the lengths of the bars
number_of_routes = totals.itervalues()

tmp = sorted(zip(countries, number_of_routes), key=lambda x : x[1], reverse=True)[:25]
countries = [x[0] for x in tmp]
number_of_airports = [x[1] for x in tmp]

# y_pos holds the position of the bars ... np.arange(N) just produces N evenly spaced ticks
y_pos = np.arange(len(countries)) 


# Plots the bar chart  
plt.barh(y_pos, number_of_airports, align='center', alpha=0.5)

# Adds the tick labels
plt.yticks(y_pos, countries)

# Sets the X label
plt.xlabel('Number of Routes')

# Sets the chart title
plt.title('Number of Arriving Routes by Country') 
 
plt.show()