## .\

# cgreverseindices.pro

## top cgReverseIndices

Utilities

`result = cgReverseIndices(ri, index [, COUNT=Long])`

Provides a simple way to obtain the data indices from a Histogram REVERSE_INDICES vector. Returns a -1 if no indices are available. Check the COUNT keyword for the number of indices returned.

### Parameters

- ri in required type=integer
The REVERSE_INDICES vector that is returned from the HISTOGRAM command.

- index in required type=integer
The zero-based index into the REVERSE_INDICES vector from which to obtain the indices. For example, an index value of 4 will return the indices in the 5th bin (zero based counting) of the histogram.

### Keywords

- COUNT out optional type=Long
The number of indices returned by the function.

:Return Value: indices: The indices that were put into the indexth bin of the histogram. A -1 is returned if no indices are in that particular bin.

### Examples

Used with the HISTOGRAM command:

```
IDL> image = cgDemoData(7)
IDL> h = Histogram(image, REVERSE_INDICES=ri)
IDL> indices = cgReverseIndices(ri, 4, COUNT=cnt)
IDL> Help, indices, cnt, h[4]
INDICES LONG = Array[948]
CNT LONG = 948
<Expression> LONG = 948
IDL> image[indices] = 0
```

### 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`

- Copyright:
Copyright (c) 2011, Fanning Software Consulting, Inc.

- History:
Written by David W. Fanning at suggestion of Ben Tupper. 7 January 2011.

## File attributes

Modification date: | Fri Mar 27 11:07:38 2015 |

Lines: | 119 |

Docformat: | rst rst |