1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4
5 namespace Linq101
6 {
7 class Aggregate
8 {
9 /// <summary>
10 /// This sample uses Count to get the number of unique factors of 300.
11 /// </summary>
12 public void Linq73()
13 {
14 int[] factorsOf300 = { 2, 2, 3, 5, 5 };
15
16 var uniqueFactors = factorsOf300.Distinct().Count();
17
18 Console.WriteLine("There are {0} unique factors of 300.", uniqueFactors);
19 }
20
21 /// <summary>
22 /// This sample uses Count to get the number of odd ints in the array.
23 /// </summary>
24 public void Linq74()
25 {
26 int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
27
28 var oddNumbers = numbers.Count(n => n % 2 == 1);
29
30 Console.WriteLine("There are {0} odd numbers in the list.", oddNumbers);
31 }
32
33 /// <summary>
34 /// This sample uses Count to return a list of customers and how many orders each has.
35 /// </summary>
36 public void Linq76()
37 {
38 List<Data.Customer> customers = Data.GetCustomerList();
39
40 var orderCounts = from c in customers
41 select new { Customer = c.CustomerID, orderCount = c.Orders.Count() };
42
43 ObjectDumper.Write(orderCounts);
44 }
45
46 /// <summary>
47 /// This sample uses Count to return a list of categories and how many products each has.
48 /// </summary>
49 public void Linq77()
50 {
51 List<Data.Product> products = Data.GetProductList();
52
53 var categoryCounts = from p in products
54 group p by p.Category
55 into g
56 select new { Category = g.Key, Count = g.Count() };
57
58 ObjectDumper.Write(categoryCounts);
59 }
60
61 /// <summary>
62 /// This sample uses Sum to get the total of the numbers in an array.
63 /// </summary>
64 public void Linq78()
65 {
66 int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
67
68 decimal total = numbers.Sum();
69
70 Console.WriteLine("The sum of the numbers is {0}", total);
71 }
72
73 /// <summary>
74 /// This sample uses Sum to get the total number of characters of all words in the array.
75 /// </summary>
76 public void Linq79()
77 {
78 string[] words = { "cherry", "apple", "blueberry" };
79
80 var totalChars = words.Sum(w => w.Length);
81
82 Console.WriteLine("There are a total of {0} characters in these words", totalChars);
83 }
84
85 /// <summary>
86 /// This sample uses Sum to get the total units in stock for each product category.
87 /// </summary>
88 public void Linq80()
89 {
90 List<Data.Product> products = Data.GetProductList();
91
92 var categories = from p in products
93 group p by p.Category
94 into g
95 select new { Category = g.Key, TotalStock = g.Sum(p => p.UnitsInStock) };
96
97 ObjectDumper.Write(categories);
98 }
99
100 /// <summary>
101 /// This sample uses Min to get the lowest number in an array.
102 /// </summary>
103 public void Linq81()
104 {
105 int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
106
107 int minNumber = numbers.Min();
108
109 Console.WriteLine("The minimum number is {0}", minNumber);
110 }
111
112 /// <summary>
113 /// This sample uses Min to get the length of the shortest word in an array.
114 /// </summary>
115 public void Linq82()
116 {
117 string[] words = { "cherry", "apple", "blueberry" };
118
119 var shortestWord = words.Min(w => w.Length);
120
121 Console.WriteLine("The shortest word is {0} characters long.", shortestWord);
122 }
123
124 /// <summary>
125 /// This sample uses Min to get the cheapest price among each category's products.
126 /// </summary>
127 public void Linq83()
128 {
129 List<Data.Product> products = Data.GetProductList();
130
131 var categroys = from p in products
132 group p by p.Category
133 into g
134 select new { Category = g.Key, CheapestPrice = g.Min(p => p.UnitPrice) };
135
136 ObjectDumper.Write(categroys);
137 }
138
139 /// <summary>
140 /// This sample uses Min to get the products with the cheapest price in each category.
141 /// </summary>
142 public void Linq84()
143 {
144 List<Data.Product> products = Data.GetProductList();
145
146 var categorys = from p in products
147 group p by p.Category
148 into g
149 let minPrice = g.Min(p => p.UnitPrice)
150 select new { Category = g.Key, CheapestProducts = g.Where(p => p.UnitPrice == minPrice) };
151
152 ObjectDumper.Write(categorys, 1);
153 }
154
155 /// <summary>
156 /// This sample uses Max to get the highest number in an array.
157 /// </summary>
158 public void Linq85()
159 {
160 int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
161
162 int maxNum = numbers.Max();
163
164 Console.WriteLine("The maximum number is {0}", maxNum);
165 }
166
167 /// <summary>
168 /// This sample uses Max to get the length of the longest word in an array.
169 /// </summary>
170 public void Linq86()
171 {
172 string[] words = { "cherry", "apple", "blueberry" };
173
174 int longestLength = words.Max(w => w.Length);
175
176 Console.WriteLine("The longest word is {0} characters long.", longestLength);
177 }
178
179 /// <summary>
180 /// This sample uses Max to get the most expensive price among each category's products.
181 /// </summary>
182 public void Linq87()
183 {
184 List<Data.Product> products = Data.GetProductList();
185
186 var categorys = from p in products
187 group p by p.Category
188 into g
189 select new { category = g.Key, price = g.Max(p => p.UnitPrice) };
190
191 ObjectDumper.Write(categorys);
192 }
193
194 /// <summary>
195 /// This sample uses Max to get the products with the most expensive price in each category.
196 /// </summary>
197 public void Linq88()
198 {
199 List<Data.Product> products = Data.GetProductList();
200
201 var categorys = from p in products
202 group p by p.Category
203 into g
204 let maxPrice = g.Max(p => p.UnitPrice)
205 select new { Category = g.Key, product = g.Where(p => p.UnitPrice == maxPrice) };
206
207 ObjectDumper.Write(categorys, 1);
208 }
209
210 /// <summary>
211 /// This sample uses Average to get the average of all numbers in an array.
212 /// </summary>
213 public void Linq89()
214 {
215 int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
216
217 double averageNumber = numbers.Average();
218
219 Console.WriteLine("The average number is {0}.", averageNumber);
220 }
221
222 /// <summary>
223 /// This sample uses Average to get the average length of the words in the array.
224 /// </summary>
225 public void Linq90()
226 {
227 string[] words = { "cherry", "apple", "blueberry" };
228
229 var averageLength = words.Average(w => w.Length);
230
231 Console.WriteLine("The average word length is {0} characters.", averageLength);
232 }
233
234 /// <summary>
235 /// This sample uses Average to get the average price of each category's products.
236 /// </summary>
237 public void Linq91()
238 {
239 List<Data.Product> products = Data.GetProductList();
240
241 var categorys = from p in products
242 group p by p.Category
243 into g
244 select new { Category = g.Key, AveragePrice = g.Average(p => p.UnitPrice) };
245
246 ObjectDumper.Write(categorys, 1);
247 }
248
249 /// <summary>
250 /// This sample uses Aggregate to create a running product on the array that calculates the total product of all elements.
251 /// </summary>
252 public void Linq92()
253 {
254 double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };
255
256 //var q = doubles.Aggregate((current, next) => current*next);
257 double product = doubles.Aggregate((runningProduct, nextFactor) => runningProduct * nextFactor);
258
259 Console.WriteLine("Total product of all numbers: {0}", product);
260 }
261
262 /// <summary>
263 /// This sample uses Aggregate to create a running account balance that subtracts each withdrawal from the initial balance of 100, as long as the balance never drops below 0.
264 /// </summary>
265 public void Linq93()
266 {
267 double startBalance = 100.0;
268
269 int[] attemptedWithdrawals = { 20, 10, 40, 50, 10, 70, 30 };
270
271 //double seed = 100;
272 //double endBalance = attemptedWithdrawals.Aggregate(seed,
273 // (current, next) => current - next > 0 ? current - next : current);
274
275 double endBalance = attemptedWithdrawals.Aggregate(startBalance,
276 (banlance, nextWithdrawal) => (nextWithdrawal <= banlance) ? (banlance - nextWithdrawal) : banlance);
277
278 Console.WriteLine(endBalance);
279 }
280 }
281 }
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