%pylab inline

# http://www.basicincome.org/bien/pdf/FiguresFAQ.pdf

max_income = 10
ubi_value = 2
gross_income = linspace(0, max_income, 11)
net_income_no_tax = gross_income
net_income_ubi_no_tax = ubi_value + gross_income # halper data
net_income_ubi = ubi_value + gross_income * 0.5 # 50% flat tax model

fig, ax = plt.subplots()

fill_between(gross_income, [ubi_value] * len(gross_income), color='green', alpha=0.2)
fill_between(gross_income, net_income_ubi_no_tax, net_income_ubi, color='yellow', alpha=0.2)
plot(gross_income, [ubi_value] * len(gross_income), ls = '--', color='black')
plot(gross_income, net_income_no_tax, color='black', alpha=0.5, label='no tax')
plot(gross_income, net_income_ubi_no_tax, ls = '--', color='black')
plot(gross_income, net_income_ubi, linewidth=2, color='black', label='after tax')

legend(loc='upper left')

xlim((0, max_income))
ax.spines['right'].set_visible(False)
ax.spines['top'].set_visible(False)
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')
title('Income distribution with basic income')
ylabel('Net Income')
xlabel('Gross Income')
text(8, 7, 'TAX', fontsize=12)
text(max_income / 2, 0.8, 'BASIC INCOME', fontsize=12, horizontalalignment='center')