;
; File: testXTLabels.ncl
;
; Author: D. Adriaansen
;
; Date: 29 Mar 2017
;
; Purpose: Demonstrate labeling the top X-axis on an X-Y plot
;
; Notes: NCL Version 6.3.0 AND 6.4.0, 
;        Linux cessna 3.16.0-4-amd64 #1 SMP Debian 3.16.36-1+deb8u2 (2016-10-19) x86_64 GNU/Linux
;________________________________________________________________________

; Generate some sample x-data
xdata = ispan(0,99,1)

; Generate some sample y-data
ydata = fspan(0,1.0,100)

; Open a workstation
wks = gsn_open_wks("png","testXTLabels")

; Set up plot resources
res = True

; GSN resources
res@gsnFrame = False
res@gsnDraw = False

; Tickmark resources
res@tmXUseBottom = False                       ; Tell NCL we don't want to use the bottom axis for both X axes
res@tmXTOn = True                              ; Turn on the top X-axis tickmarks
res@tmXTMode = "Explicit"                      ; Explicitly position and label the top X-axis tickmarks
res@tmXTValues = (/0,25,50,75,99/)             ; Values for where to put the tickmarks
res@tmXTLabels = (/"0","25","50","75","99"/)   ; Corresponding strings to use for labels of the top X-axis tickmarks
res@tmXBOn = False                             ; Turn off the bottom X-axis tickmarks to see if it has any effect

; Plot
plot = gsn_csm_xy(wks,xdata,ydata,res)
draw(plot)
frame(wks)