java.lang.Object
- edu.princeton.cs.algs4.StdStats

```
public final class StdStats
extends java.lang.Object
```
The StdStats class provides static methods for computing statistics such as min, max, mean, sample standard deviation, and sample variance.
For additional documentation, see Section 2.2 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

方法概要

修饰符和类型	方法	说明
`static void`	`main(java.lang.String[] args)`	Unit tests `StdStats`.
`static double`	`max(double[] a)`	Returns the maximum value in the specified array.
`static double`	`max(double[] a, int lo, int hi)`	Returns the maximum value in the specified subarray.
`static int`	`max(int[] a)`	Returns the maximum value in the specified array.
`static double`	`mean(double[] a)`	Returns the average value in the specified array.
`static double`	`mean(double[] a, int lo, int hi)`	Returns the average value in the specified subarray.
`static double`	`mean(int[] a)`	Returns the average value in the specified array.
`static double`	`min(double[] a)`	Returns the minimum value in the specified array.
`static double`	`min(double[] a, int lo, int hi)`	Returns the minimum value in the specified subarray.
`static int`	`min(int[] a)`	Returns the minimum value in the specified array.
`static void`	`plotBars(double[] a)`	Plots bars from (0, a_i) to (a_i) for each i to standard draw.
`static void`	`plotLines(double[] a)`	Plots the line segments connecting (i, a_i) to (i+1, a_i+1) for each i to standard draw.
`static void`	`plotPoints(double[] a)`	Plots the points (0, a₀), (1, a₁), ..., (n-1, a_n-1) to standard draw.
`static double`	`stddev(double[] a)`	Returns the sample standard deviation in the specified array.
`static double`	`stddev(double[] a, int lo, int hi)`	Returns the sample standard deviation in the specified subarray.
`static double`	`stddev(int[] a)`	Returns the sample standard deviation in the specified array.
`static double`	`stddevp(double[] a)`	Returns the population standard deviation in the specified array.
`static double`	`stddevp(double[] a, int lo, int hi)`	Returns the population standard deviation in the specified subarray.
`static double`	`var(double[] a)`	Returns the sample variance in the specified array.
`static double`	`var(double[] a, int lo, int hi)`	Returns the sample variance in the specified subarray.
`static double`	`var(int[] a)`	Returns the sample variance in the specified array.
`static double`	`varp(double[] a)`	Returns the population variance in the specified array.
`static double`	`varp(double[] a, int lo, int hi)`	Returns the population variance in the specified subarray.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 方法详细资料
  - max
```
public static double max(double[] a)
```
    Returns the maximum value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the maximum value in the array a[]; Double.NEGATIVE_INFINITY if no such value
  - max
```
public static double max(double[] a,
                         int lo,
                         int hi)
```
    Returns the maximum value in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the maximum value in the subarray a[lo..hi); Double.NEGATIVE_INFINITY if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - max
```
public static int max(int[] a)
```
    Returns the maximum value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the maximum value in the array a[]; Integer.MIN_VALUE if no such value
  - min
```
public static double min(double[] a)
```
    Returns the minimum value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the minimum value in the array a[]; Double.POSITIVE_INFINITY if no such value
  - min
```
public static double min(double[] a,
                         int lo,
                         int hi)
```
    Returns the minimum value in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the maximum value in the subarray a[lo..hi); Double.POSITIVE_INFINITY if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - min
```
public static int min(int[] a)
```
    Returns the minimum value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the minimum value in the array a[]; Integer.MAX_VALUE if no such value
  - mean
```
public static double mean(double[] a)
```
    Returns the average value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the average value in the array a[]; Double.NaN if no such value
  - mean
```
public static double mean(double[] a,
                          int lo,
                          int hi)
```
    Returns the average value in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the average value in the subarray a[lo..hi); Double.NaN if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - mean
```
public static double mean(int[] a)
```
    Returns the average value in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the average value in the array a[]; Double.NaN if no such value
  - var
```
public static double var(double[] a)
```
    Returns the sample variance in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the sample variance in the array a[]; Double.NaN if no such value
  - var
```
public static double var(double[] a,
                         int lo,
                         int hi)
```
    Returns the sample variance in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the sample variance in the subarray a[lo..hi); Double.NaN if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - var
```
public static double var(int[] a)
```
    Returns the sample variance in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the sample variance in the array a[]; Double.NaN if no such value
  - varp
```
public static double varp(double[] a)
```
    Returns the population variance in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the population variance in the array a[]; Double.NaN if no such value
  - varp
```
public static double varp(double[] a,
                          int lo,
                          int hi)
```
    Returns the population variance in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the population variance in the subarray a[lo..hi); Double.NaN if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - stddev
```
public static double stddev(double[] a)
```
    Returns the sample standard deviation in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the sample standard deviation in the array a[]; Double.NaN if no such value
  - stddev
```
public static double stddev(int[] a)
```
    Returns the sample standard deviation in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the sample standard deviation in the array a[]; Double.NaN if no such value
  - stddev
```
public static double stddev(double[] a,
                            int lo,
                            int hi)
```
    Returns the sample standard deviation in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the sample standard deviation in the subarray a[lo..hi); Double.NaN if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - stddevp
```
public static double stddevp(double[] a)
```
    Returns the population standard deviation in the specified array.
    
    参数:
    
    a - the array
    
    返回:
    
    the population standard deviation in the array; Double.NaN if no such value
  - stddevp
```
public static double stddevp(double[] a,
                             int lo,
                             int hi)
```
    Returns the population standard deviation in the specified subarray.
    
    参数:
    
    a - the array
    
    lo - the left endpoint of the subarray (inclusive)
    
    hi - the right endpoint of the subarray (exclusive)
    
    返回:
    
    the population standard deviation in the subarray a[lo..hi); Double.NaN if no such value
    
    抛出:
    
    java.lang.IllegalArgumentException - if a is null
    
    java.lang.IllegalArgumentException - unless (0 <= lo) && (lo < hi) && (hi <= a.length)
  - plotPoints
```
public static void plotPoints(double[] a)
```
    Plots the points (0, a₀), (1, a₁), ..., (n-1, a_n-1) to standard draw.
    
    参数:
    
    a - the array of values
  - plotLines
```
public static void plotLines(double[] a)
```
    Plots the line segments connecting (i, a_i) to (i+1, a_i+1) for each i to standard draw.
    
    参数:
    
    a - the array of values
  - plotBars
```
public static void plotBars(double[] a)
```
    Plots bars from (0, a_i) to (a_i) for each i to standard draw.
    
    参数:
    
    a - the array of values
  - main
```
public static void main(java.lang.String[] args)
```
    Unit tests StdStats. Convert command-line arguments to array of doubles and call various methods.
    
    参数:
    
    args - the command-line arguments

类 StdStats

方法概要

从类继承的方法 java.lang.Object

方法详细资料

max

max

max

min

min

min

mean

mean

mean

var

var

var

varp

varp

stddev

stddev

stddev

stddevp

stddevp

plotPoints

plotLines

plotBars

main