looping over panel plots is very slow

Dear all,

I have a ncl code, in which I have roughly 50*5 plots which I want to
plot alltogether in a pdf with gsn_panel.
I am plotting 5 plots on one page, resulting in 50 pages. For this, I am
looping over gsn_panel.
The code works fine for a small amount of pages, but it takes VERY long
for this high number of pages.

Is there any chance to reduce the running time of the code?

As the code is rather long and also refers to other functions defined in different codes, I only send the relevant code snippet, where I loop over the panel plots.
Secondly, I attach a simplified code, which is ready to run. However, here the looping works quite fast. Therefore, I guess the slowing down has something to do with all the indexing within the loop in the original code.

Here is the code snippet from my original code to illustrate the problem:

----------------------------------------------------------------------------------
; calculate page number
n_pages = n_total

;---set panel resources
     panel_res = True ; specify desired panel mods

     panel_res@gsnFrame = False ; Don't advance frame. because add labelbar
     panel_res@gsnMaximize = True
     panel_res@gsnPaperOrientation = "portrait"

     panel_res@gsnPanelCenter = False ; don't center the plots

         tx3Res = True
         tx3Res@txJust = "CenterLeft"

         gsRes = True ; set polyline resources
         gsRes@gsLineThicknessF = 3.0 ; Extra thick lines

         if (nd .eq. 4) ; 4 plots on one page --> change legend position
             xleg = (/ (/0.90,0.92/), (/0.90,0.92/), (/0.90,0.92/), (/0.90,0.92/) /)
             yleg = (/ (/0.47,0.47/), (/0.44,0.44/), (/0.41,0.41/), (/0.38,0.38/) /)
             tx3Res@txFontHeightF = 0.013 ; Font Height for legend labels
         else
             xleg = (/ (/0.68,0.70/), (/0.68,0.70/), (/0.68,0.70/), (/0.68,0.70/) /)
             yleg = (/ (/0.11,0.11/), (/0.08,0.08/), (/0.05,0.05/), (/0.02,0.02/) /)
             tx3Res@txFontHeightF = 0.013 ; Font Height for legend labels
         end if

         xtxt = (/ xleg(0,1)+0.01, xleg(0,1)+0.01, xleg(0,1)+0.01, xleg(0,1)+0.01 /)
         ytxt = (/ yleg(0,0), yleg(1,0), yleg(2,0), yleg(3,0) /)
         

    ;---panel plot, how many plots on one page in x and y direction?
     if (nd .ge. 5)
         panel_ny = 3
     else
         panel_ny = 2
     end if
     
         panel_mx = 2

do i = 0, n_pages-1
     print(round(int2flt(i)/n_pages*100,2) + " % of panel created")

     panel_res@txString = "Wind roses " + position_name(ind_total(i)) + \
                          " (" + height_dir_model_korrel( ind_total(i) ) + " m)" + "~C~" +\ ;~C~ forces a line break: ~I~ writes the letters in indexal size
                          "~I~" + time_strings_post_selection(0) + " - " +time_strings_post_selection(dim_selection-1) ; + model_name + case_number

     gsn_panel(wks, plot(:,ind_total(i)), (/ panel_ny, panel_mx /), panel_res)

     do j = 0, nd-2 ; legend for circles
             gsRes@gsLineColor = colors(j)
             gsn_polyline_ndc(wks,xleg(j,:),yleg(j,:),gsRes)
     end do

     gsn_text_ndc(wks,plot_name(:nd-2),xtxt(:nd-2),ytxt(:nd-2),tx3Res)

     gsn_labelbar_ndc(wks,nbar,labels,0.1,0.98,lbres) ; add labelbar
     frame(wks)
     delete(panel_res@txString)
end do

----------------------------------------------------------------------------------------

And here is the simplified code, which is ready to run:
----------------------------------------------------------------------------------------
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin
outpath = ; to be defined

x = ispan(0,10,1)
y = ispan(0,10,1)

plot = new( (/5,50/), graphic )

fn = outpath + "panel_loops_test"
wks = gsn_open_wks("pdf", fn)

res = True
res@gsnDraw = False
res@gsnFrame = False ; do not advance the frame

do i = 0,49
     do j = 0,4
         plot(j,i) = gsn_csm_xy(wks,x,y,res)
     end do
end do

; draw panels
     n_pages = 50

     panel_res = True ; specify desired panel mods

     panel_res@gsnFrame = False ; Don't advance frame. because add labelbar
     panel_res@gsnMaximize = True
     panel_res@gsnPaperOrientation = "portrait"
     panel_res@gsnPanelCenter = False ; don't center the plots

     do i = 0,n_pages-1
         gsn_panel(wks, plot(:,i), (/ 3, 2 /), panel_res)
         frame(wks)
     end do

end
---------------------------------------------------------------------------------------------------

Any help is appreciated very much! Thank you!

Best regards,
Julia

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Received on Tue Jan 28 08:22:01 2014