item_sale_avg['Price Category'] = np.where(item_sale_avg.Sales <= 500, 'low',
np.where(item_sale_avg.Sales >= 1500, 'high', 'medium'))
print (item_sale_avg)
Sales Price Category
0 100 low
1 500 low
2 600 medium
3 1500 high
4 2000 high