//1.Summon
public static double getSum(double[] arr){
double sum = 0;
for(int i =0;i < ;i++){
sum += arr[i];
}
return sum;
}
//2. Find the average
public static double getMean(double[] arr){
return getSum(arr) / ;
}
//3. Find the mode
public static double getMuch(double[] arr){
/*Method 1
//Construct the mapping of corresponding relationships
Map<Double,Integer> map = new HashMap<Double,Integer>();
for(int i = 0;i < ;i++){
if((arr[i])){
//containsKey(Object key) Returns true if this map contains the mapping relationship of the specified key.
//get(Object key) returns the value mapped by the specified key; if this map does not contain the mapping relationship of the key, return null.
//put(K key, V value) associates the specified value with the specified key in this map (optional action).
(arr[i], (arr[i])+1);
}else{
(arr[i], 1);
}
}
int maxCount = 0;//Number of initialization occurrences
double much = -1;//Initialize mode
//Iterator
Iterator<Double> iter = ().iterator();
while(()){
//next() returns the next element of the iteration
double num = ();
int count = (num);
if(count > maxCount){
maxCount = count;
much = num;
}
}
return much;
*/
//Method 2
if( == 1){
return arr[0];
}
int count = 0;
int max = 0;
double much = 0;
(arr);
for(int i = 0;i < - 1;i ++){
if(arr[i] == arr[i+1]){
count ++ ;
}else{
count = 0;
}
if(count > max){
max = count;
much = arr[i];
}
}
return much;
}
//4. Find the median number
public static double getMedian(double[] arr){
if( % 2 == 0){
//If the original array is an even number, the median is the average of the two in the middle
return ((arr[/2]+arr[/2-1])/2);
}else{
//If the original array is an odd number, the median is the middle number
return arr[/2];
}
}
//5. Seek extreme differences
public static double getRange(double[] arr){
double max = arr[0],min = arr[0];
for(int i = 0;i<;i++){
if(arr[i]>max){
max = arr[i];
}
if(arr[i]<min){
min = arr[i];
}
}
return max-min;
}
//6. Find the variance
public static double getVariance(double[] arr){
double variance = 0 ;
double mean = getMean(arr);
double sum = 0;
for(int i=0;i<;i++){
sum += (arr[i]-mean)*(arr[i]-mean);
}
variance = sum/;
return variance;
}
//7. Find the standard deviation
public static double getStandardDevition(double[] arr){
return (getVariance(arr));
}