CODEWITHSUNDEEP
javamath
rablentain
rablentain

Reputation: 6745

Determine average value

I have to calculate an average value of my simulation. The simulation is ongoing and I want (for each iteration) to print the current average value. How do I do that?

I tried the code below (in the loop), but I do not think that the right value is calculated...

int average = 0;
int newValue; // Continuously updated value.

if(average == 0) {
    average = newValue;
}

average = (average + newValue)/2;

I also taught about store each newValue in an array and for each iteration summarize the whole array and do the calculation. However, I don't think that's a good solution, because the loop is an infinity loop so I can't really determine the size of the array.

There is also a possibility that I am thinking too much and that the code above is actually correct, but I don't think so...

Upvotes: 0

Views: 168

Answers (8)

OldCurmudgeon
OldCurmudgeon

Reputation: 65889

To do it the oop way:

class Average {
  private int count;
  private int total;

  public void add ( int value ) {
    this.total += value;
    this.count += 1;
  }

  public int get () {
    return total / count;
  }
}

Upvotes: 0

Geobits
Geobits

Reputation: 22342

You don't have to keep track of the total, or multiply the average by the number of iterations. You can instead weight the new value and add it directly to the average. Something like:

int count = 0;
double average;

while (/*whatever*/)
{
    double weighted = (newValue - average) / ++count;
    average += weighted;
}

Upvotes: 0

Caleryn
Caleryn

Reputation: 1084

I would keep a running total and a count of iterations, sadly not recursive.

long total = 0;
int count = 0;

while ((int newValue = getValue()) > -1) // or other escape condition
{
   total += newValue;
   long average = total / ++count;
   System.out.println(average);
}

Upvotes: 6

Ron Teller
Ron Teller

Reputation: 1890

Another possibility:

double newValue, average;
int i = 1;

while(some_stop_condition)
{
    newValue = getValue();

    average = (average*(i-1) + newValue)/i;
    i++;
}

Upvotes: 1

Sam I am says Reinstate Monica
Sam I am says Reinstate Monica

Reputation: 31206

Or, if you want to do this the easy way, don't actually compute your average until you need to display it or use it. Just keep the sum, and the count, and wherever you need an average just do

System.out.println("Average: " + (sum/count));

if you want to prevent division by zero, you can use the Ternary operator

System.out.println("Average: " + (count == 0 ? 0 : sum/count));

Upvotes: 0

PM 77-1
PM 77-1

Reputation: 13352

Since some of the posters here seem to be mathematically challenged, let me state the obvious:

It's possible to get a relation between Average(n) and Average(n+1):

Average(n+1) = (Average(n)*n + new_value)/(n+1)

assuming that average is calculated with enough precision.

So it should be possible to create a recursion, though for OP purposes it simply not needed.

Upvotes: 1

Kavan
Kavan

Reputation: 340

In your loop, just keep adding each newValue onto a variable which just keeps incrementing by each newValue for each iteration and keep a record of how many times this happens with a 'counting' variable. Then to get the average for that iteration, just divide the total by the number of values taken into account.

int total = 0;
int count = 0;

// Whatever your loop is...
for(;;) {

    // Add the new value onto the total
    total += newValue;
    // Record the number of values added
    count ++;

    // Calculate the average for this iteration
    int average = total / count;
}

Upvotes: 0

Scientist
Scientist

Reputation: 1464

Try below code snippet:

double RecursiveAvg(double A[], int i, int n)  
{  
    //Base case  
    if (i == n-1) return A[i]/n;  

    return A[i]/n + RecursiveAvg(A, i + 1, n);  
}

Upvotes: 0

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