[ncl-talk] Problem of using "get_isolines"

[王淼]

Hi Mary,
   I put the "pt_miao.nc"(just one month data) in the "incoming" folder , because I cannot see the list of this folder ,I'm not sure if I succeed .So I attached it , you can download for testing.
Hope this helps.
Miao


-----原始邮件-----
发件人:"Mary Haley" <haley at ucar.edu>
发送时间:2017-06-02 05:16:12 (星期五)
收件人: "王淼" <miaowang2015 at pku.edu.cn>
抄送: "ncl-talk at ucar.edu" <ncl-talk at ucar.edu>
主题: Re: [ncl-talk] Problem of using "get_isolines"


Hi,


We were looking into this problem using a different example, and seeing some odd results.


Is it possible for you to provide us with the pt.nc file?


You can use our ftp, if the file is not too large:


http://www.ncl.ucar.edu/report_bug.shtml#HowToFTP



Thanks,


--Mary




On Tue, May 30, 2017 at 8:17 PM, 王淼 <miaowang2015 at pku.edu.cn> wrote:
Hi Ncl Talk,
   I used get_isolines to get the points that define a contour line .When I printed the longitude of these points ,  the distribution of the longitude wasn't the same(gonna show in the following example) ,may be [0~-360] or [20~-340],etc. I have expected the function may return the longitude as [0~360] or [-180~180]. I googled it ,but didn't help.I still don't know what caused the effect, so I ask you for help. Thanks!


Here is the code and resluts:


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/contrib/cd_string.ncl"


begin


f1=addfile("pt.nc","r")         ;pt(time,lat,lon)
pt=short2flt(f1->pt)              
pt=lonFlip(pt)                  ;lon=0~360degrees   


n=dimsizes(pt&time)




  wks = gsn_open_wks("pdf","sypt_all")        
  
  res                      = True         
  res at gsnDraw              = False
  res at gsnFrame             = False


  res at cnFillOn             = False         
  res at cnLinesOn            = True      


  res at cnLevelSelectionMode   = "ExplicitLevels"   
  res at cnLevels              = (/350,360/) 


  
  res at mpMinLatF            = 0         
  res at mpCenterLonF         =180           
res at trGridType = "TriangularMesh"   




do i = 0, n-1                                           ;time
    plot=gsn_csm_contour_map_ce(wks, pt(i,:,:), res)  
    
     isolines = get_isolines(plot at contour,"plot")   
     
    do j= 0, ListCount(isolines) - 1
      iso := isolines[j]             
      
      idx=maxind(iso at n_points)
      b = iso at start_point(idx)          
      e = b + iso at n_points(idx) - 1       
      y := iso(0,b:e)                  
      x := iso(1,b:e)                   ;y=lat,x=lon
      print(x)
    end do
end do
end 


| result1 | result2 |
| 0 | 0 |
| -1.8 | -1.3 |
| -2.5 | -2.5 |
|      … |      … |
| -358.9 | -339.8 |
| -359.7 | -340 |
| -360 |      … |
| | 20 |
| | 18.6 |
| |      … |
| | 2.5 |
| | 0.5 |
| | 0 |





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