LinQ: C# sort an array while copying with some filters

Question

I have a case like, I have to fetch the non zero values of an array, sort them and find the median of values. I did as follows,

var array2 = (from t in array1 where t.array2 != 0 select t.array2).ToArray();
Array.Sort(array2);
var Median = array2.Length % 2 == 0 ? new List<double>() { ((array2[array2.Length / 2 - 1]) + (array2[array2.Length / 2])) / 2 } : new List<double>() { array2[array2.Length / 2] };

For now all going fine. But I am thinking of merging the first two lines in a single one like, copying the non zero values using orderby method. For this I have tried like,

var array2 = (from t in ipedsTableValue where t.array2 != 0 select t.array2).ToArray(t); // Not worked

Also suggest me if there are any super way to calculate median of an array in C# because that line is also looking so big and I am afraid that is not easily readable.

I have referred SO resource: Add a Median Method to a List Though it is working fine, I am thinking of some simple and efficient code with some less number of codes. Any suggestion would be helpful!

Modified your initial line, to suggest that you want to fetch non zero values in an array, sort them (which is required for a median) and calculate Median. It was misleading to suggest that you need to copy to another array, which caused the initial discrepancy in my first solution. — Mrinal Kamboj
– Mrinal Kamboj, Commented Oct 19, 2016 at 14:17

Hamid Pourjam · Accepted Answer · 2016-10-19 08:41:37Z

1

You can use linq and a conditional operator.

var filterd = array1
    .Where(x => x.array2 != 0)
    .Select(x => x.array2)
    .OrderBy(x => x)
    .ToArray();

var length = filterd.Length;

var median = length % 2 == 0
    ? (filterd[length / 2 - 1] + filterd[length / 2]) / 2.0
    : filterd[length / 2];

edited Oct 19, 2016 at 8:41

answered Oct 19, 2016 at 8:27

Hamid Pourjam

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1 Comment

Jeya Suriya Muthumari Over a year ago

Thanks for the reply, I am getting error like, Operator '!=' cannot be applied to operands of type I used.

Misiakw · Accepted Answer · 2016-10-19 08:42:34Z

1

It should look something like that

var median = array2.Take((array2.Length%2 == 0) ? ((array2.Length/2) + 1) : ((array2.Length + 1)/2))
                    .Reverse()
                    .Take((array2.Length%2 == 0) ? 2 : 1)
                    .Sum(x => x);

answered Oct 19, 2016 at 8:42

Misiakw

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Comments

Mrinal Kamboj · Accepted Answer · 2016-10-19 11:04:24Z

1

Array copy and ordering operation:

var filteredArray = array1.Where(x => x != 0.0).OrderBy(x => x).ToArray();

Calculate Median

double midpoint = (filteredArray.Count() - 1) / 2.0;
double median = (filteredArray[(int)(midpoint)] + filteredArray[(int)(midpoint + 0.5)]) / 2.0;

edited Oct 19, 2016 at 11:04

answered Oct 19, 2016 at 8:44

Mrinal Kamboj

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1 Comment

Mrinal Kamboj Over a year ago

I misunderstood your initial requirement as copying all the elements to another array except 0th element, I have now modified to remove the 0.0 values and calculated median

TomFarCry · Accepted Answer · 2016-10-19 09:55:32Z

0

Try like this

var array2= (from t in array1 where t.array2!= 0 select t.array2).OrderBy(t => t).ToArray();

answered Oct 19, 2016 at 9:55

TomFarCry

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2 Comments

Jeya Suriya Muthumari Over a year ago

That's amazing. Thanks TomFarCry

Mrinal Kamboj Over a year ago

Where's median calculation ?

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