from pylab import show, plot, ylabel, xlabel, barh, yticks, title, grid
import sys
import time
always_true = 1
labels = []
total_expenses = []
while always_true == 1:
    try:
        categories = int(input('How many categories would you like on your expenditures chart? '))
    except ValueError:
        print ('Invalid input.')
        time.sleep(3)
        sys.exit()
    if categories > 0:
        print ('No problem!')
        break
    else:
        print ('Invalid input.')
while categories > 0:
    category_name = input('Enter a categoty: ')
    try:
        expenses = int(input('Enter your expenses: '))
    except ValueError:
        print ('Invalid input.')
        sys.exit()
    if expenses > 0:
        print ('OK!')
    else:
        print ('Invalid input.')
    labels.append(category_name)
    total_expenses.append(expenses)
    categories -= 1
num_bars = len(total_expenses)
positions = range(1, num_bars + 1)
barh(positions, total_expenses, align = 'center')
yticks(positions, labels)
ylabel('Category')
xlabel('Money spent')
title('Expenditures chart')
grid()
show()