[ncl-talk] Frequency to days conversion and draw a vertical line in the plot

[Dennis Shea]

See Example 5 at:
    http://www.ncl.ucar.edu/Applications/spec.shtml

Good Luck

On Thu, Mar 10, 2016 at 5:32 AM, Nanda Kishore Reddy <nandu.eng at gmail.com>
wrote:

> Hi ncl-users,
>
>                 I am very new to the NCL software and I would like to do
> spectrum analysis with confidence levels. I have tried with the existing
> code and plotted, but, I just need some help like how to plot x-axis in the
> form of *Days *(i.e. 1/frequency) instead of the *frequency (days/cycle) *otherwise
> top axis should be in Days and bottom axis should be in frequency (if it is
> possible).
>                 I have, just need one more help like how to draw a
> vertical line in the plot (x=0.05,y=1000) from the below attached figure.
>
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"
>
> begin
> buoy = asciiread("ad08_sw_mons_2014_wspd_davg.txt",(/122,1/),"float")
>
> d   = 0        ; detrending opt: 0=>remove mean 1=>remove mean + detrend
> sm  = 0        ; smooth: should be at least 3 and odd
> pct = 0.1      ; percent taper: (0.0 <= pct <= 1.0) 0.10 common.
>
> ;************************************************
> ; calculate spectrum
> ;************************************************
> sdof = specx_anal(buoy(:,0),d,sm,pct)
> ;print (sdof)
> ;exit
> ;************************************************
> ; calculate confidence interval [here 5 and 95%]
> ; return 4 curves to be plotted
> ;************************************************
> splt = specx_ci (sdof, 0.05, 0.99)
>
> ;************************************************
> ; plotting
> ;************************************************
> wks  = gsn_open_wks("x11","spec")              ; Opens a ps file
>
> r = True                                                         ; plot
> mods desired
> r at tiMainString = "AD08 wind speed"           ; title
> r at tiXAxisString = "Frequency (cycles/Days)"    ; xaxis
> r at tiYAxisString = "Variance"                     ; yaxis
> r at trYLog              = True                          ; log scaling
> ;r at trXMinF = 0
> ;r at trXMaxF = 0.2
> ;r at trYMinF             = 1                            ; manually set
> lower limit
> ;r at trYMaxF             = 1000.0                  ;   "          upper
> r at gsnFrame            = False                    ; do not advance frame
> r at xyLineThicknesses   = (/2.,1.,1.,1./)
> r at xyDashPatterns      = (/0,0,1,1/)
> r at xyLineColors        = (/"foreground","green","blue","red"/)
> plot  = gsn_csm_xy(wks,sdof at frq, splt,r)
> lnid =
> gsn_add_polyline(wks,plot,(/0.05,0.1,0.1,0.1/),(/0.0001,0,0,1000/),r)
>
> xf   = (/0.40, 0.40+sdof at bw/)                ; Create band width line
> ys   = 0.60*max(sdof at spcx)                   ; 75% up Y axis
> yv   = (/ys,ys/)
> rpl  = True                                                ; resources for
> polyline
> rpl at gsLineThicknessF  = 2                    ; Define line thickness
> ;gsn_polyline(wks,plot,xf,yv,rpl)             ; Draw BandWidth
>
> txres= True                                                ; label BW line
> txres at txFontHeightF = 0.015                  ; font height
> txres at txJust        = "CenterLeft"               ; Set lable location
> ;gsn_text(wks,plot,"BW",0.41+sdof at bw,ys,txres)    ; Label
> frame (wks)
> end
>
>
>
>
> With Kind Regards
> Nanda Kishore reddy. B
> Senior Research Fellow
> Ocean Observation Systems
> NIOT, INDIA
>
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