Package stdlib

# Class StdStats

java.lang.Object
stdlib.StdStats

public final class StdStats extends Object
Standard statistics. This class provides methods for computing statistics such as min, max, mean, sample standard deviation, and sample variance.

For additional documentation, see Section 2.2 of Introduction to Programming in Java: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

• ## Constructor Summary

Constructors
Modifier
Constructor
Description
`private `
`StdStats()`

• ## Method Summary

Modifier and Type
Method
Description
`static void`
`main(String[] args)`
Test client.
`static double`
`max(double[] a)`
Return maximum value in array, -infinity if no such value.
`static double`
```max(double[] a, int lo, int hi)```
Return maximum value in subarray a[lo..hi], -infinity if no such value.
`static int`
`max(int[] a)`
Return maximum value of array, Integer.MIN_VALUE if no such value
`static double`
`mean(double[] a)`
Return average value in array, NaN if no such value.
`static double`
```mean(double[] a, int lo, int hi)```
Return average value in subarray a[lo..hi], NaN if no such value.
`static double`
`mean(int[] a)`
Return average value in array, NaN if no such value.
`static double`
`min(double[] a)`
Return minimum value in array, +infinity if no such value.
`static double`
```min(double[] a, int lo, int hi)```
Return minimum value in subarray a[lo..hi], +infinity if no such value.
`static int`
`min(int[] a)`
Return minimum value of array, Integer.MAX_VALUE if no such value
`static void`
`plotBars(double[] a)`
Plot bars from (0, a[i]) to (i, a[i]) to standard draw.
`static void`
`plotLines(double[] a)`
Plot line segments connecting points (i, a[i]) to standard draw.
`static void`
`plotPoints(double[] a)`
Plot points (i, a[i]) to standard draw.
`static double`
`stddev(double[] a)`
Return sample standard deviation of array, NaN if no such value.
`static double`
```stddev(double[] a, int lo, int hi)```
Return sample standard deviation of subarray a[lo..hi], NaN if no such value.
`static double`
`stddev(int[] a)`
Return sample standard deviation of array, NaN if no such value.
`static double`
`stddevp(double[] a)`
Return population standard deviation of array, NaN if no such value.
`static double`
```stddevp(double[] a, int lo, int hi)```
Return population standard deviation of subarray a[lo..hi], NaN if no such value.
`static double`
`sum(double[] a)`
Return sum of all values in array.
`static double`
```sum(double[] a, int lo, int hi)```
Return sum of all values in subarray a[lo..hi].
`static int`
`sum(int[] a)`
Return sum of all values in array.
`static double`
`var(double[] a)`
Return sample variance of array, NaN if no such value.
`static double`
```var(double[] a, int lo, int hi)```
Return sample variance of subarray a[lo..hi], NaN if no such value.
`static double`
`var(int[] a)`
Return sample variance of array, NaN if no such value.
`static double`
`varp(double[] a)`
Return population variance of array, NaN if no such value.
`static double`
```varp(double[] a, int lo, int hi)```
Return population variance of subarray a[lo..hi], NaN if no such value.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ## Constructor Details

• ### StdStats

private StdStats()
• ## Method Details

• ### max

public static double max(double[] a)
Return maximum value in array, -infinity if no such value.
• ### max

public static double max(double[] a, int lo, int hi)
Return maximum value in subarray a[lo..hi], -infinity if no such value.
• ### max

public static int max(int[] a)
Return maximum value of array, Integer.MIN_VALUE if no such value
• ### min

public static double min(double[] a)
Return minimum value in array, +infinity if no such value.
• ### min

public static double min(double[] a, int lo, int hi)
Return minimum value in subarray a[lo..hi], +infinity if no such value.
• ### min

public static int min(int[] a)
Return minimum value of array, Integer.MAX_VALUE if no such value
• ### mean

public static double mean(double[] a)
Return average value in array, NaN if no such value.
• ### mean

public static double mean(double[] a, int lo, int hi)
Return average value in subarray a[lo..hi], NaN if no such value.
• ### mean

public static double mean(int[] a)
Return average value in array, NaN if no such value.
• ### var

public static double var(double[] a)
Return sample variance of array, NaN if no such value.
• ### var

public static double var(double[] a, int lo, int hi)
Return sample variance of subarray a[lo..hi], NaN if no such value.
• ### var

public static double var(int[] a)
Return sample variance of array, NaN if no such value.
• ### varp

public static double varp(double[] a)
Return population variance of array, NaN if no such value.
• ### varp

public static double varp(double[] a, int lo, int hi)
Return population variance of subarray a[lo..hi], NaN if no such value.
• ### stddev

public static double stddev(double[] a)
Return sample standard deviation of array, NaN if no such value.
• ### stddev

public static double stddev(double[] a, int lo, int hi)
Return sample standard deviation of subarray a[lo..hi], NaN if no such value.
• ### stddev

public static double stddev(int[] a)
Return sample standard deviation of array, NaN if no such value.
• ### stddevp

public static double stddevp(double[] a)
Return population standard deviation of array, NaN if no such value.
• ### stddevp

public static double stddevp(double[] a, int lo, int hi)
Return population standard deviation of subarray a[lo..hi], NaN if no such value.
• ### sum

public static double sum(double[] a)
Return sum of all values in array.
• ### sum

public static double sum(double[] a, int lo, int hi)
Return sum of all values in subarray a[lo..hi].
• ### sum

public static int sum(int[] a)
Return sum of all values in array.
• ### plotPoints

public static void plotPoints(double[] a)
Plot points (i, a[i]) to standard draw.
• ### plotLines

public static void plotLines(double[] a)
Plot line segments connecting points (i, a[i]) to standard draw.
• ### plotBars

public static void plotBars(double[] a)
Plot bars from (0, a[i]) to (i, a[i]) to standard draw.
• ### main

public static void main(String[] args)
Test client. Convert command-line arguments to array of doubles and call various methods.