REVERSE Function

Standard Library function that reverses a vector or array for a given dimension.

enabled.

Usage

result = REVERSE(array, [dimension])

Input Parameters

array—The vector or array to be reversed.

dimension—(optional) An integer specifying which dimension of array to reverse. By default, the 0th dimension is reversed.

Note:

The dimension argument breaks with PV-WAVE convention of 0-based indexing and is instead 1-based. That is, the 0th dimension of an array is specified by a 1 and the first dimension by a 2.

Returned Value

result—The vector or array that has been reversed.

Keywords

None.

Example 1

This example exhibits the result of applying REVERSE to a 4‑by‑3 integer array.

; Create a 4-by-3 integer array. Each element has a value equal 

; to its one-dimensional subscript.

a = INDGEN(4, 3)

PRINT, a

; PV-WAVE prints:

; 0       1       2       3

; 4       5       6       7

; 8       9      10      11

; Reverse the rows of a.

PRINT, REVERSE(a)

; PV-WAVE prints:

; 3       2       1       0

; 7       6       5       4

; 11      10       9       8

; Reverse the columns of a.

PRINT, REVERSE(a, 2)

; PV-WAVE prints:

; 8       9      10      11

; 4       5       6       7

; 0       1       2       3

; Reverse the columns and rows of a.

PRINT, REVERSE(REVERSE(a), 2)

; PV-WAVE prints:

; 11      10       9       8

; 7       6       5       4

; 3       2       1       0

Example 2

The following commands first display the image contained in the scientist3.dat file, and then rotate and redisplay it:

image1 = BYTARR(250, 200)

OPENR, unit, !Data_dir + 'scientist3.dat', /Get_lun

READU, unit, image1

FREE_LUN, unit

WINDOW, Xsize=500, Ysize=200

TV, image1, 0

TV, REVERSE(image1), 1