[amesmich]

Heres some arduino code we used. We altered it greatly but it shoudl get you started.

/* This script is designed to take several readings from the maxbotix sonar and generate a mode/median.
Author: Jason Lessels
Date created: 2011/June/06
Lisence: GPL (=>2)
This work has been compileed using many sources mainly posts/wiki posts from;
Allen, Bruce (2009/July/23) and Gentles, Bill (2010/Nov/12)
*/ 


//Set the pin to recieve the signal.
const int pwPin = 7;
//variables needed to store values
int arraysize = 9; //quantity of values to find the median (sample size). Needs to be an odd number 


//declare an array to store the samples. not necessary to zero the array values here, it just makes the code clearer
int rangevalue[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0};
long pulse;
int modE;
 void setup() { 

  //Open up a serial connection
  Serial.begin(9600);
  //Wait for the serial connection
  delay(500);



}
//Main loop where the action takes place
void loop() { 
  pinMode(pwPin, INPUT);


  for(int i = 0; i < arraysize; i++)
  {								    


    pulse = pulseIn(pwPin, HIGH);
    rangevalue[i] = pulse/58;
    delay(10);
  }


  Serial.print("Unsorted: ");
  printArray(rangevalue,arraysize);
  isort(rangevalue,arraysize);
  Serial.print("Sorted: ");
  printArray(rangevalue,arraysize);
  modE = mode(rangevalue,arraysize);
  Serial.print("The mode/median is: ");
  Serial.print(modE);
  Serial.println();
  delay(1000);


} 


/*-----------Functions------------*/ //Function to print the arrays.
void printArray(int *a, int n) { 

  for (int i = 0; i < n; i++)
  {
    Serial.print(a[i], DEC);
    Serial.print(' ');
  }


  Serial.println();


} 


//Sorting function
// sort function (Author: Bill Gentles, Nov. 12, 2010)
void isort(int *a, int n){
// *a is an array pointer function

  for (int i = 1; i < n; ++i)
  {
    int j = a[i];
    int k;
    for (k = i - 1; (k >= 0) && (j < a[k]); k--)
    {
      a[k + 1] = a[k];
    }
    a[k + 1] = j;
  }


} 


//Mode function, returning the mode or median.
int mode(int *x,int n){ 
  int i = 0;
  int count = 0;
  int maxCount = 0;
  int mode = 0;
  int bimodal;
  int prevCount = 0;


  while(i<(n-1)){


    prevCount=count;
    count=0;


    while(x[i]==x[i+1]){


      count++;
      i++;
    }


    if(count>prevCount&count>maxCount){
      mode=x[i];
      maxCount=count;
      bimodal=0;
    }
    if(count==0){
      i++;
    }
    if(count==maxCount){//If the dataset has 2 or more modes.
      bimodal=1;
    }
    if(mode==0||bimodal==1){//Return the median if there is no mode.
      mode=x[(n/2)];
    }
    return mode;
  }


}