Linq Array filter or range

David Smith

Vuples where are you lololol?

using linq i want multilpty to multiply (Aarray1 * Array2) from 2.3 to 2.05 then i want to sum the output array base upon the range , can some help me

Array1[0] = {( 2.00, 1.00 )}   * Array2[0] = {( 2.00, 2.00 )} = 2
Array1[1] = {( 2.01, 2.00 )}   *   Array2[1] = {( 2.01, 3.00 )} = 6
Array1[2] = {( 2.02, 3.00 )} * Array2[2] = {( 2.02, 4.00 )} = 12
Array1[3] = {( 2.03, 4.00 )}   * Array2[3] = {( 2.03, 5.00 )} = 20
Array1[4] = {( 2.04, 5.00 )}   * Array2[4] = {( 2.04, 6.00 )} = 30
Array1[5] = {( 2.05, 6.00 )}   *   Array2[5] = {( 2.05, 7.00 )} = 42
Array1[6] = {( 2.06, 7.00 )}   *   Array2[6] = {( 2.06, 8.00 )} = 56
-----------------------------------------------------------------------



Output[0] = {( 2.03, 20)}
Output[1] = {( 2.04, 30 )}
Output[2] = {( 2.05, 42 )}

double result = Output.Sum();

result = 92

13 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
This should work:

using System;
using System.Linq;

class Program
{
static void Main()
{
var Array1 = new double[7][];
Array1[0] = new double[]{ 2.00, 1.00 };
Array1[1] = new double[]{ 2.01, 2.00 };
Array1[2] = new double[]{ 2.02, 3.00 };
Array1[3] = new double[]{ 2.03, 4.00 };
Array1[4] = new double[]{ 2.04, 5.00 };
Array1[5] = new double[]{ 2.05, 6.00 };
Array1[6] = new double[]{ 2.06, 7.00 };

var Array2 = new double[7][];
Array2[0] = new double[]{ 2.00, 2.00 };
Array2[1] = new double[]{ 2.01, 3.00 };
Array2[2] = new double[]{ 2.02, 4.00 };
Array2[3] = new double[]{ 2.03, 5.00 };
Array2[4] = new double[]{ 2.04, 6.00 };
Array2[5] = new double[]{ 2.05, 7.00 };
Array2[6] = new double[]{ 2.06, 8.00 };

double result = Array1.Where(a => a[0] >= 2.03 && a[0] <= 2.05).Zip(Array2.Where(a => a[0] >= 2.03 && a[0] <= 2.05), (a1, a2) => a1[1] * a2[1]).Sum();
Console.WriteLine(result);
Console.ReadKey();
}
}
David Smith14y ago
yea i prefer to break it up, i was curious. I have caught on the syntax when adding multiple expressions to one equation to one linq. I am still trying to learn it in the mist.
Vulpes14y ago
When calculating 'result', just replace List1 and List2 with the expressions that have been assigned to them.

BTW, it's not good coding practice IMO to always cram everything into a single LINQ query. Remember you (or somebody else) may have to maintain this stuff months or years down the line.

Whilst LINQ is a powerful tool, it can produce some very complex expressions and it may therefore be better to break them up into bits that are easy to understand.
David Smith14y ago
how to put in one linq all together, im curious
Vulpes14y ago
OK, I've changed List1 and List2 to make this a little easier:

var List1 = ArrayDictionary[ArrayType.Array1.ToString()].Where(t => t.Item1 >= 2.03 && t.Item1 <= 2.05);
var List2 = ArrayDictionary[ArrayType.Array2.ToString()].Where(t => t.Item1 >= 2.03 && t.Item1 <= 2.05);

double result = List1.Zip(List2, (t1, t2) => t1.Item2 * t2.Item2).Sum()/ List1.Sum(t => t.Item2);
Console.WriteLine(result); // 6.13 recurring
David Smith14y ago
The last step is to divide by sum of Array1 from 2.3 to 2.05.   So now we have to just add the divide part to the existing linq we have now you did the previous reply

Array1[3] = {( 2.03, 4.00 )}   * Array2[3] = {( 2.03, 5.00 )} = 20
Array1[4] = {( 2.04, 5.00 )}   * Array2[4] = {( 2.04, 6.00 )} = 30
Array1[5] = {( 2.05, 6.00 )}   *   Array2[5] = {( 2.05, 7.00 )} = 42

--------------------------------------------------------------------
Array1[3] = {( 2.03, 4.00 )}
Array1[4] = {( 2.04, 5.00 )}
Array1[5] = {( 2.05, 6.00 )}

92 / 15 = 6.1333333333

output = 6.13333333
Vulpes14y ago
Sorry, forgot I hadn't attended to this last night :(

Here's a version of the program which should work for your ArrayDictionary:

using System;
using System.Linq;
using System.Collections.Generic;

enum ArrayType
{
Array1,
Array2,
Array3
}

class Program
{
static void Main()
{
var ArrayDictionary = new Dictionary>>();

var list1 = new List>();
list1.Add(Tuple.Create( 2.00, 1.00 ));
list1.Add(Tuple.Create( 2.01, 2.00 ));
list1.Add(Tuple.Create( 2.02, 3.00 ));
list1.Add(Tuple.Create( 2.03, 4.00 ));
list1.Add(Tuple.Create( 2.04, 5.00 ));
list1.Add(Tuple.Create( 2.05, 6.00 ));
list1.Add(Tuple.Create( 2.06, 7.00 ));
ArrayDictionary.Add(ArrayType.Array1.ToString(), list1);

var list2 = new List>();
list2.Add(Tuple.Create( 2.00, 2.00 ));
list2.Add(Tuple.Create( 2.01, 3.00 ));
list2.Add(Tuple.Create( 2.02, 4.00 ));
list2.Add(Tuple.Create( 2.03, 5.00 ));
list2.Add(Tuple.Create( 2.04, 6.00 ));
list2.Add(Tuple.Create( 2.05, 7.00 ));
list2.Add(Tuple.Create( 2.06, 8.00 ));
ArrayDictionary.Add(ArrayType.Array2.ToString(), list2);

var List1 = ArrayDictionary[ArrayType.Array1.ToString()];
var List2 = ArrayDictionary[ArrayType.Array2.ToString()];

double result = List1.Where(t => t.Item1 >= 2.03 && t.Item1 <= 2.05).Zip(List2.Where(t => t.Item1 >= 2.03 && t.Item1 <= 2.05), (t1, t2) => t1.Item2 * t2.Item2).Sum();
Console.WriteLine(result);
Console.ReadKey();
}
}
David Smith14y ago
did you come up with anything yet, i posted the actually logic i am trying to use in the previous post.
David Smith14y ago
Dictionary>> ArrayDictionary = new Dictionary>>();

    for (waveLength = 2.00, index = 0; waveLength <= 5.00; waveLength += 0.01, index++)
            {
                Output[index] = (ArrayDictionary[ArrayType.Array1.ToString()][index].Item2 * ArrayDictionary[ArrayType.Array2.ToString()][index].Item2);

                ArrayDictionary[ArrayType.ArrayType.ToString()].Add(new Tuple(waveLength, Output[index]));

            }

              double output = ArrayDictionary[ArrayType.Array1.ToString()].Where(a => a[0] >= LowLimit && a[0] <=
                        HighLimit).Zip(ArrayDictionary[ArrayType.Array2.ToString()].to.Where(a => a[0] >= 2.03 && a[0] <=
                        2.(t1, t2) => t1[1].Item2 * t2[1].Item2).Sum();
Vulpes14y ago
Because Array1[3] and Array1[0] are both arrays of doubles and we want the first element of the latter array.

The logic won't work as it stands with ArrayDictionary which - the last time I looked - was a Dictionary, not an array of double arrays.

However, I notice you're talking again about tuples so, if you can tell me how it's currently defined, I'll try and adapt the logic to work with that.
David Smith14y ago
So why start at a[0], when the element that i wanted started at Array1[3] and not Array1[0]. Also below my tuple is not working with the logic, i am getting a systax error, but your console app is working. I am getting error where you see the highlight a[0]

double output = ArrayDictionary[ArrayType.Array1.ToString()].Where(a => a[0] >= LowLimit && a[0] <=
HighLimit).Zip(ArrayDictionary[ArrayType.Array1.ToString()].to.Where(a => a[0] >= 2.03 && a[0] <=
2.(t1, t2) => t1[1].Item2 * t2[1].Item2).Sum();
Vulpes14y ago
Well, Array1 and Array2 are both arrays of double arrays.

They therefore implement IEnumerable and so (for LINQ purposes) are sequences of double arrays.

As each element in the sequence is an array ('a') and we're interested in the first element, we therefore use a[0].
David Smith14y ago
Im curious. why did you use a[0], can you explain

Where(a => a[0] >= 2.03 && a[0]