Question

我正在学习LINQ，我想从以下列表中找到最便宜的产品：

List<Product> products = new List<Product> { 
                new Product {Name = "Kayak", Price = 275M, ID=1}, 
                new Product {Name = "Lifejacket", Price = 48.95M, ID=2}, 
                new Product {Name = "Soccer ball", Price = 19.50M, ID=3}, 
            };

我已经提出以下内容，但不知何故感觉这不是最好的方法：

var cheapest = products.Find(p => p.Price == products.Min(m => m.Price));

你能告诉我正确的方法吗？

Answer 1

您应该使用MinBy：

public static TSource MinBy<TSource>(
    this IEnumerable<TSource> source,
    Func<TSource, IComparable> projectionToComparable
) {
    using (var e = source.GetEnumerator()) {
        if (!e.MoveNext()) {
            throw new InvalidOperationException("Sequence is empty.");
        }
        TSource min = e.Current;
        IComparable minProjection = projectionToComparable(e.Current);
        while (e.MoveNext()) {
            IComparable currentProjection = projectionToComparable(e.Current);
            if (currentProjection.CompareTo(minProjection) < 0) {
                min = e.Current;
                minProjection = currentProjection;
            }
        }
        return min;                
    }
}

只需将此作为方法添加到public static班级（EnumerableExtensions？）。

现在你可以说

var cheapest = products.MinBy(x => x.Price);

Answer 2

或者，您可以简单地对它们进行排序并获取第一个结果，假设您在Product对象之后而不是Price值;像这样。

var cheapestProduct = products.OrderBy(p => p.Price).FirstOrDefault();
var mostExpensiveProduct = products.OrderByDescending(p => p.Price).FirstOrDefault();

Answer 3

您需要先按价格订购，然后选择第一个。

if(products.Any()){
    var productWithCheapestPrice = products.OrderBy(p => p.Price).First();
}

使用LINQ查找价格最便宜的产品？

3 个答案: