public void Execute()
{
var numbers = new[]
{
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
};
//
// Average拡張メソッドは、文字通り平均を求める拡張メソッド。
//
// Average拡張メソッドには、各基本型のオーバーロードが用意されており
// (decimal, double, int, long, single及びそれぞれのNullable型)
// それぞれに、引数無しとselectorを指定するバージョンのメソッドがある。
//
//
// 引数無しのAverage拡張メソッドの使用.
//
Output.WriteLine("引数無し = {0}", numbers.Average());
//
// selectorを指定するAverage拡張メソッドの使用.
//
Output.WriteLine("引数有り = {0}", numbers.Average(item => item%2 == 0 ? item : 0));
}
public static void Test(Assert assert)
{
assert.Expect(20);
int[] numbers = { 2, 2, 3, 5, 5, -1, 2, -1 };
string[] words = { "one", "two", "three" };
double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };
// TEST
int uniqueNumbers = numbers.Distinct().Count();
assert.DeepEqual(uniqueNumbers, 4, "Count() distinct numbers");
// TEST
int oddNumbers = numbers.Count(n => n % 2 == 1);
assert.DeepEqual(oddNumbers, 3, "Count() odd numbers");
// TEST
var groupJoin = (from g in Group.GetGroups()
join p in Person.GetPersons() on g.Name equals p.Group into pg
select new { Group = g.Name, PersonCount = pg.Count() })
.ToArray();
var groupJoinExpected = new object[] {
new { Group = "A", PersonCount = 1 },
new { Group = "B", PersonCount = 4 },
new { Group = "C", PersonCount = 2 },
new { Group = "D", PersonCount = 0 }
};
assert.DeepEqual(groupJoin, groupJoinExpected, "Count() within joint collections");
// TEST
var grouped = (from p in Person.GetPersons()
group p by p.Group into g
select new { Group = g.Key, PersonCount = g.Count() })
.ToArray();
var groupedExpected = new object[] {
new { Group = "A", PersonCount = 1 },
new { Group = "C", PersonCount = 2 },
new { Group = "B", PersonCount = 4 },
new { Group = (string)null, PersonCount = 1 }
};
assert.DeepEqual(grouped, groupedExpected, "Count() within group");
// TEST
double numSum = numbers.Sum();
assert.DeepEqual(numSum, 17, "Sum() numbers");
// TEST
double totalChars = words.Sum(w => w.Length);
assert.DeepEqual(totalChars, 11, "Sum() total chars");
// TEST
var groupedSum = (from p in Person.GetPersons()
group p by p.Group into g
select new { Group = g.Key, Sum = g.Sum(x => x.Count) })
.ToArray();
var groupedSumExpected = new object[] {
new { Group = "A", Sum = 300 },
new { Group = "C", Sum = 600 },
new { Group = "B", Sum = 2000 },
new { Group = (string)null, Sum = 3000 }
};
assert.DeepEqual(groupedSum, groupedSumExpected, "Sum() within group");
// TEST
int minNum = numbers.Min();
assert.DeepEqual(minNum, -1, "Min() number");
// TEST
int shortestWordLength = words.Min(w => w.Length);
assert.DeepEqual(shortestWordLength, 3, "Min() for shortest word");
// TEST
var groupedMin = (from p in Person.GetPersons()
group p by p.Group into g
select new { Group = g.Key, Min = g.Min(x => x.Count) })
.ToArray();
var groupedMinExpected = new object[] {
new { Group = "A", Min = 300 },
new { Group = "C", Min = 100 },
new { Group = "B", Min = 50 },
new { Group = (string)null, Min = 3000 }
};
assert.DeepEqual(groupedMin, groupedMinExpected, "Min() within group");
// TEST
var groupedMinWithLet = (from p in Person.GetPersons()
group p by p.Group into g
let minCount = g.Min(x => x.Count)
select new { Group = g.Key, Name = g.Where(x => x.Count == minCount).Select(x => x.Name).ToArray() })
.ToArray();
var groupedMinWithLetExpected = new object[] {
new { Group = "A", Name = new[]{ "Frank"} },
new { Group = "C", Name = new[]{ "Zeppa"} },
new { Group = "B", Name = new[]{ "Dora"} },
new { Group = (string)null, Name = new[]{ "Nemo"} }
};
assert.DeepEqual(groupedMinWithLet, groupedMinWithLetExpected, "Min() within group with let");
// TEST
int maxNum = numbers.Max();
assert.DeepEqual(maxNum, 5, "Max() number");
// TEST
int longestWordLength = words.Max(w => w.Length);
assert.DeepEqual(longestWordLength, 5, "Max() for longest word");
// TEST
var groupedMax = (from p in Person.GetPersons()
group p by p.Group into g
select new { Group = g.Key, Max = g.Max(x => x.Count) })
.ToArray();
var groupedMaxExpected = new object[] {
new { Group = "A", Max = 300 },
new { Group = "C", Max = 500 },
new { Group = "B", Max = 700 },
new { Group = (string)null, Max = 3000 }
};
assert.DeepEqual(groupedMax, groupedMaxExpected, "Max() within group");
// TEST
var groupedMaxWithLet = (from p in Person.GetPersons()
group p by p.Group into g
let maxCount = g.Max(x => x.Count)
select new { Group = g.Key, Name = g.Where(x => x.Count == maxCount).Select(x => x.Name).ToArray() })
.ToArray();
var groupedMaxWithLetExpected = new object[] {
new { Group = "A", Name = new[]{ "Frank"} },
new { Group = "C", Name = new[]{ "Billy"} },
new { Group = "B", Name = new[]{ "John", "Mary"} },
new { Group = (string)null, Name = new[]{ "Nemo"} }
};
assert.DeepEqual(groupedMaxWithLet, groupedMaxWithLetExpected, "Max() within group with let");
// TEST
double averageNum = numbers.Average();
assert.DeepEqual(averageNum, 2.125, "Average() number");
// TEST
var averageWordLengths = new[] { "1", "22", "333", "4444", "55555" };
double averageWordLength = averageWordLengths.Average(w => w.Length);
assert.DeepEqual(averageWordLength, 3, "Average() for word lengths");
// TEST
var groupedAverage = (from p in Person.GetPersons()
group p by p.Group into g
select new { Group = g.Key, Average = g.Average(x => x.Count) })
.ToArray();
var groupedAverageExpected = new object[] {
new { Group = "A", Average = 300 },
new { Group = "C", Average = 300 },
new { Group = "B", Average = 500 },
new { Group = (string)null, Average = 3000 }
};
assert.DeepEqual(groupedAverage, groupedAverageExpected, "Average() within group");
// TEST
var doublesForAggregate = new[] { 1.0, 2.0, 3.0, 4.0, 5.0 };
double product = doublesForAggregate.Aggregate((runningProduct, nextFactor) => runningProduct * nextFactor);
assert.DeepEqual(product, 120, "Aggregate() within doubles");
// TEST
var startBalance = 100.0;
var attemptedWithdrawals = new[] { 20, 10, 40, 50, 10, 70, 30 };
var endBalance =
attemptedWithdrawals.Aggregate(startBalance,
(balance, nextWithdrawal) =>
((nextWithdrawal <= balance) ? (balance - nextWithdrawal) : balance));
assert.DeepEqual(endBalance, 20, "Aggregate() balance");
}
