LINQ - Data Query Operations

1public class DataAnalyzer
2{
3    public IEnumerable<CustomerSummary> GetTopCustomers(List<Order> orders, int count)
4    {
5        return orders
6            .Where(o => o.Status == OrderStatus.Completed)
7            .GroupBy(o => o.CustomerId)
8            .Select(g => new CustomerSummary
9            {
10                CustomerId = g.Key,
11                TotalOrders = g.Count(),
12                TotalSpent = g.Sum(o => o.Total),
13                AverageOrderValue = g.Average(o => o.Total)
14            })
15            .OrderByDescending(c => c.TotalSpent)
16            .Take(count);
17    }
18 
19    public Dictionary<string, decimal> GetSalesByCategory(List<Product> products)
20    {
21        return products
22            .GroupBy(p => p.Category)
23            .ToDictionary(
24                g => g.Key,
25                g => g.Sum(p => p.Price * p.QuantitySold)
26            );
27    }
28}