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.

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