Creates and draws an XY plot with two different X axes.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl" function gsn_csm_x2y ( wks  : graphic, x1 : numeric, x2 : numeric, y : numeric, res1  : logical, res2  : logical ) return_val  : graphic
The X coordinates of the first curve.x2
The X coordinates of each curve. The x1 curve will be represented on the bottom axis, and the x2 curve will be represented on the top axis.y
The Y coordinates of both curves.res1
A variable containing an optional list of plot resources for the first X curve, attached as attributes. Set to True if you want the attached attributes to be applied, and False if you either don't have any resources to set, or you don't want the resources applied.
Note that for setting resources that don't particularly apply to a specific plot, like frame maximization (gsnMaximize), a main title (tiMainString), or the three subtitles at the top (gsnLeftString, gsnCenterString, gsnRightString), you should set these resources with res1, and not res2.res2
A variable containing an optional list of plot resources for the second X curve, attached as attributes. Set to True if you want the attached attributes to be applied, and False if you either don't have any resources to set, or you don't want the resources applied.
The res2 resources should only be resources that apply specifically to the x2/y2 data that you are plotting (see example below).
The return value is the scalar id of the first XY plot created.
The scalar id of the second XY plot is returned as an attribute called "xy2". This attribute or the return value can be used in calls to functions like gsn_add_polymarker or gsn_add_polyline to add primitives to either plot.
The id of the data object is returned as an attribute called data. This is useful if you want to use setvalues to change some data options after this function has been called.
This function creates and draws an XY plot on the given workstation, with two different X axes represented. By default, the tickmarks will point outward. The plot id returned is the one that represents the left Y axis. The right axis plot id is returned as an attribute of the return value called "xy2".
As with a regular XY plot, NCL will try to pick "nice" values for the X axes. This means that your two X axes may not line up as expected. To control the X axes so that the min/max of each has the min/max of your actual data, set the trXMinF and trXMaxF resources. For example:
res1@trXMinF = min(x1) res1@trXMaxF = max(x1) res2@trXMinF = min(x2) res2@trXMaxF = max(x2)
If any of x1, x2, or y has a _FillValue attribute, this value will be used as a missing value.
Note that if x2@long_name is set, this would normally be used to label the X axis. However, since labeling the top axis along with the possibility of a main title and/or three subtitles could cause quite a bit of clutter, the long_name attribute is ignored in this case. If you want it to appear, set tiXAxisString explicitly:
res2@tiXAxisString = x2@long_nameThere are other special gsn resources that apply to XY plots. See the gsn resource page for a full list.
To maximize the area that the plot is drawn in, set the special resource gsnMaximize to True.
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl" begin ; ; Read in data ; f = addfile("TestData.xy3.nc" , "r") p = f->P(0,0:35) ; read in left variable (y1) t = f->T(0,0:35) ; read in right variable (y2) time = f->time(0:35) ; this is our x wks = gsn_open_wks("ps","gsn_csm_plot_x2y") ; left variable resB = True resB@vpWidthF = 0.6 resB@vpHeightF = 0.8 resB@gsnMaximize = True resB@xyLineThicknesses = 2. ; thicker line resB@tiXAxisString = t@long_name +" "+"[solid]" ; axis string ; right variable resT = True resT@xyDashPatterns = 1 ; dashed line for 2nd resT@xyLineThicknesses = 2 ; thicker line resT@tiXAxisString = p@long_name +" "+"[dash]" ; axis string plot = gsn_csm_x2y(wks,t,p,time,resB,resT) ;*********************************** ; second plot: offset and color ;*********************************** resB@vpWidthF = 0.4 resB@vpHeightF = 0.8 resB@trXMaxF = 16. ; axis max resB@trXMinF = 0. ; axis min resB@tiMainString = "Curves Offset" ; title resB@tiMainOffsetYF = 0.10 ; move title up. resB@xyLineColors = "blue" ; line color resT@trXMaxF = 1024. ; axis max resT@trXMinF = 1008. ; axis min resT@xyLineColors = "red" ; line color plot = gsn_csm_x2y(wks,t,p,time,resB,resT) end