CODEWITHSUNDEEP
c#arrays
LeonidasFett
LeonidasFett

Reputation: 3132

Write frequency of numbers in one array into another

I am writing a little app for statistics. A function of this app will be determining the frequency of randomly generated numbers in an Array which holds 100 elements.

So far, I managed to generate a two-dimensional Array which I have filled with the numbers 0-100 (these are max and min of randomly generated numbers in the other Array).

I thought of filling this array with the frequency based on the index.

Like this:

//Array for random numbers
int[] randomNumbers = new int[10] {2, 3, 4, 5, 5, 2, 8, 9, 3, 7};

//Two-dimensional array for holding frequency of each unique number
int[,] frequency = new int[2,101];

for (int i = 0; i <= 100; i++)
{
    frequency[0, i] = i;
}

The frequency array gets generated fine. But I don't know where to go from here. How could I add the frequency of each unique number to the array? I tried this:

for (int i = 0; i < randomNumbers.Length; i++)
{
    frequency[1, i] = frequency[1, i] + 1;
}

But it just fills the frequency array with ones continuously.

Upvotes: 1

Views: 2594

Answers (6)

KaraokeStu
KaraokeStu

Reputation: 768

You should be able to do this:

int[] randomNumbers = new int[10] {2, 3, 4, 5, 5, 2, 8, 9, 3, 7};

Dictionary<int, int> dictionary = new Dictionary<int,int>();

foreach(int randomNumber in randomNumbers)
{
    if (!dictionary.ContainsKey(randomNumber))
        dictionary.Add(randomNumber, 1);
    else
        dictionary[randomNumber]++;
}

If you then want to sort them, use Linq...

var sortedList = from pair in dictionary
    orderby pair.Key
    select pair;

Upvotes: 2

Michael Gunter
Michael Gunter

Reputation: 12811

I think you're looking for something like this:

int[] randomNumbers = ...;
int[] frequency = new int[101];
for (int i = 0, l = randomNumbers.Length; i < l; ++i)
    ++frequency[randomNumbers[i]];

The result of this is that the frequency array contains the number of occurrences for each index. In other words frequency[0] will contain the number of occurrences of the value 0, frequency[1] will contain the number of occurrences of the value 1, etc...

Upvotes: 2

Nolonar
Nolonar

Reputation: 6122

To me, it looks like a Dictionary<int, int> is what's best suited to your needs:

Dictionary<int, int> frequency = new Dictionary<int, int>();

foreach (int number in randomNumbers)
{
    if (frequency.ContainsKey(number))
        frequency[number]++;
    else
        frequency.Add(number, 1);
}

int numberOfGroups = frequency.Count;

Upvotes: 2

Mateusz
Mateusz

Reputation: 2317

I would do it that way, you have index in frequency table as value of number and actual value is frequency (just something like that not exactly):

for (int i = 0; i <= 100; i++)
{
    frequency[i] = randomNumbers.SelectMany( o=>o.ArrayProperty==i ).Count() ;
}

Upvotes: 2

XtrmJosh
XtrmJosh

Reputation: 939

You may find it useful to have two arrays, and each time you generate a random number, you would set the next element of the first array to the number, and set the random numberth element of the second array to itself +1. This will give you statistics from the start (from POV of the random number generator.

int[] vals, stats;

vals = new int[100]
stats = new int[100]

for (int i = 0; i < 100; i++)
{
    vals[i] = getRandom();
    stats[vals[i]] = stats[vals[i]] + 1;
}

Something like that might do the trick :)

Upvotes: 2

Servy
Servy

Reputation: 203834

GroupBy makes this pretty straightforward.

var frequencies = randomNumbers.GroupBy(n => n)
    .Select(group => new 
             {
                Number = group.Key, 
                Frequency = group.Count() 
             });

Upvotes: 12

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