import matplotlib.pyplot as plt
import json
movies= json.load(open('movies.json',encoding='utf-8'))
rating=[]
durations=[]
for m in movies:
    durations.append(m['duration'])
plt.title("时长分布")        
plt.xlabel("min")      
plt.figure(figsize=(8,5))
plt.hist(durations,bins=5,color='green')
plt.savefig('q4_3b_hist.png',dpi=150)