# bar chart

import numpy as np
import matplotlib.pyplot as plt

names = ("Ben", "Pui", "Fah", "Ton", "Kob")
n = len(names)

x_pos = np.arange(n)
perf  = np.loadtxt("sales.csv", delimiter=",", skiprows=1)
perf_range = np.max(perf,axis=1) - np.min(perf,axis=1)
perf_avg   = np.mean(perf,axis=1)
plt.bar(x_pos, perf_avg, yerr=perf_range, 
        align='center',alpha=0.4)
plt.xticks(x_pos, names)
plt.ylabel('Sales (Millions)')
plt.title('Weekly Sales Performance')
plt.show()