# Coyote Graphics Routines For Sale

## Date: Sat Nov 23 09:39:47 2013

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# cgpercentiles.pro

## top cgPercentiles

Math

`result = cgPercentiles(data [, Dimension=integer] [, Percentiles=float])`

This program calculates user-specified percentiles of a data set. A percentile is the value of a variable below which a certain percent of observations fall. In other words, 75% of the values in a data set fall below the 75th percentile of the data. Computing percentiles is really nothing more than counting in a sorted input array. A box-and-whisker plot usually will display the 25th, 50th, and 75th percentiles. This is a commercial version of the cgPercentiles program in the Coyote Library and contains a `Dimension` keyword to allow calculations over a single dimension of a multiple dimension data set.

This program set can be purchased from the Coyote Store.

### Return value

The return value is either a scalar or vector of data values corresponding to the number of percentiles asked for with the `Percentiles` keyword, or a -1 if there is an error in the program.

### Parameters

data in required

The data from which percentiles are desired. A vector or an array.

### Keywords

Dimension in optional type=integer

Set this keyword to perform the percentile calculation over this dimension of the input data. The result will be an array that is the size of the percentilies vector in X and the size of this dimension of the data in Y.

Percentiles in optional type=float

Set this keyword to a scalar or vector of values between 0.0 and 1.0 to indicate the percentile desired. A value of 0.5 indicates the 50th percentile. Default value is [0.25, 0.50, 0.75].

### Examples

To return percentile values for 0.25, 0.50, and 0.75 of a data set:

``` IDL> data = Randomu(3L, 100) * 100 IDL> Print, cgPercentiles(data, Percentiles=[0.25, 0.5, 0.75]) 27.4920 45.3172 69.3138 ```
To perform the percentile calculation in the third dimension of a 3D array:
``` IDL> data = Indgen(15, 10, 5) IDL> Print, cgPercentiles(data, Percentiles=[0.25, 0.5, 0.75], Dimension=3) 37.0000 75.0000 112.000 187.000 225.000 262.000 337.000 375.000 412.000 487.000 525.000 562.000 637.000 675.000 712.000 ```

### Author information

Author:

FANNING SOFTWARE CONSULTING:

``` David W. Fanning 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: david@idlcoyote.com Coyote's Guide to IDL Programming: http://www.idlcoyote.com ```

``` Written, 3 June 2013 by David W. Fanning. Added DIMENSION keyword. 11 November 2013. DWF. ```