CODEWITHSUNDEEP
c#linq
Mechanik
Mechanik

Reputation: 679

LINQ - C# - Using lambda - Get a set of data from a Collection

I have a struct TimePoint which is similar to a Point except, the x value is a datetime, an observable collection of these timepoints and a method that takes a datetime and returns a double value.

I want to retrieve the max and min value of the doubles that are returned from the datetimes in this collection.

I am new to linq and am unable to figure out the query I would have to pass on the observable collection to achieve this.

Here's what I am trying to get:

double minDouble = 0;
double maxDouble = 0;

foreach(TimePoint item in obsColl)
{
    var doubleVal = ConvertToDouble(item.X); //Here x is a datetime
    if(minDouble > doubleVal)
        minDouble = doubleVal;
    if(maxDouble < doubleVal)
        maxDouble = doubleVal;
}

How can I achieve this using LINQ? Or is LINQ not ideal for this?

Upvotes: 5

Views: 326

Answers (4)

bradgonesurfing
bradgonesurfing

Reputation: 32182

Using the fluent assertion package

    [Microsoft.VisualStudio.TestTools.UnitTesting.TestMethod]
    public void MyTestMethod()
    {
        var list = new List<double>() { 1, 3, 5, 2, 9, 4 };

        var minmax = from l in list
                     group l by 1 into g
                     select new
                     {
                         min = g.Min(),
                         max = g.Max()
                     };

        minmax.First().min.Should().Be(1);
        minmax.First().max.Should().Be(9);
    }

Now the group l by 1 into g is a hack because linq will not allow aggregates without groups but it is not too bad

Upvotes: 0

makc
makc

Reputation: 2579

you can go over this examples 101 LINQ Samples

Upvotes: 3

Mujassir Nasir
Mujassir Nasir

Reputation: 1720

It is more efficient

    double minDouble =ConvertToDouble( obsColl.Min(item => item.X));
    double maxDouble = ConvertToDouble(obsColl.Max(item => item.X));

Upvotes: 2

McGarnagle
McGarnagle

Reputation: 102753

You can use Max and Min for this:

double minDouble = obsColl.Min(item => ConvertToDouble(item.X));
double maxDouble = obsColl.Max(item => ConvertToDouble(item.X));

Upvotes: 4

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