[ncl-talk] Color filled contour disappears with contour_shade pattern

Adam Phillips asphilli at ucar.edu
Thu May 2 12:42:35 MDT 2019


Hi SB,
The plot that is going to be overlaid cannot be created by calling
gsn_csn_contour_map. You should use gsn_csm_contour instead. So switch this:
  plot2 =  gsn_csm_contour_map(wks,rain,res)
with this:
  plot2 =  gsn_csm_contour(wks,rain,res)
Adam


On Thu, May 2, 2019 at 11:59 AM S Br <sbr.climate at gmail.com> wrote:

> Hi Rick,
> You have correctly guessed my query. Now, I have checked that the new
> variable 'rain' is correctly defined with the value gt/lt .39/-.39 but I am
> still struggling to overlay this value with patterns with
> another gsn_csm_contour_map. I am copying here the last part of my program.
> Am I doing somewhere wrong? Else, do I need to send a second resources
> (res2) for the 2nd plot?
>
>    plot1 =  gsn_csm_contour_map(wks,rain,res)
>
>   res at cnMonoFillPattern = True
>   res at cnFillPattern = 12
>   rain = where(rain.lt. .39 .and. rain.gt. -.39, rain at _FillValue, rain)
>   plot2 =  gsn_csm_contour_map(wks,rain,res)
>   overlay(plot1,plot2)
>
>   draw(plot1)
>   frame(wks)
>
>
>
>
>
>
>
> On Thu, May 2, 2019 at 6:03 PM Rick Brownrigg <brownrig at ucar.edu> wrote:
>
>>
>> So my (very limited) understanding from the code you sent, you drew a
>> color-filled contour plot of the variable "rain", which was a time slice of
>> the variable precip from the file. Then you intended to use gsn_csm_shade
>> to hachure regions where rain was gt/lt .39/-.39 ?
>>
>> This is speculation:
>>
>> i) draw your color-filled plot as before
>>
>> ii) mask out the rain variable for only the values you want:
>>
>>    rain = where(rain.lt. .39 .and. rain.gt. -.39, rain at _FillValue, rain)
>>
>> iii) redraw the rain variable with gsn_csm_contour_map as before, but
>> using cnFillPatterns instead of color
>>
>> iv) overlay the two plots as in the coneff_14 example (this requires you
>> set res at gsnFrame = False and res at gsnDraw = False)
>>
>> HTH...
>> Rick
>>
>>
>>
>> On Thu, May 2, 2019 at 10:30 AM S Br <sbr.climate at gmail.com> wrote:
>>
>>> Hi Rick,
>>> Thanks for your reply but my region of interest cover a regional lat/lon
>>> domain, so I can't use gsn_csm_contour(). Instead, I am using
>>> gsn_csm_contour_map().
>>> Actually, my main objective is to draw a correlation plot with contour
>>> filled with color and then mark pattern to the region having significant
>>> correlation value (see the map attached).
>>> For example, I have calculated the threshold value of correlation to be
>>> significant is 0.39. So, I want to draw patterns over the filled contour
>>> for the region having the correlation value below -0.39 and above 0.39.
>>> 'gsn_contour_shade' is working fine for this but unfortunately, I can't
>>> use this with gsn_csm_contour_map()
>>>
>>> Is there any otherway to achieve this?
>>>
>>> Thanks.
>>> SB
>>>
>>>
>>>
>>>
>>>
>>> On Thu, May 2, 2019 at 4:45 PM Rick Brownrigg <brownrig at ucar.edu> wrote:
>>>
>>>> The docs for gsn_contour_shade() state:
>>>>
>>>> You cannot mix and match color and shading with this routine. For an
>>>> example of drawing shaded and filled contours, see example
>>>> coneff_14.ncl <http://ncl.ucar.edu/Applications/coneff.shtml#ex14>.
>>>>
>>>> However, that example coneff_14 shows how to achieve the result via two
>>>> calls to gsn_csm_contour():
>>>>
>>>> http://ncl.ucar.edu/Applications/coneff.shtml#ex14
>>>>
>>>> Hope that helps...
>>>> Rick
>>>>
>>>> On Thu, May 2, 2019 at 5:39 AM S Br <sbr.climate at gmail.com> wrote:
>>>>
>>>>> Hi Users,
>>>>> I am trying to plot a contour map filled with color and then apply
>>>>> patterns to the values greater and smaller than the specified values using
>>>>> the function gsn_contour_shade(plot,0.5,3.0,opt)
>>>>>
>>>>> However, when I use the gsn_contour_shade and overlay, the contour
>>>>> filled with color disappears. I can only see the patterns without the
>>>>> filled contour. Please have a look at the attached image.
>>>>>  I am using NCL6.4.0 and my script is given below.
>>>>>
>>>>> Thank you, SB
>>>>>
>>>>> begin
>>>>>
>>>>>  in1 = addfile("precip.gpcp.mon.mean.nc","r")
>>>>>   rain=in1->precip(0,:,:)
>>>>>   printVarSummary(rain)
>>>>> ;************************************
>>>>> ;create plot
>>>>> ;************************************
>>>>>   wks = gsn_open_wks("pdf","overlay")             ; send graphics to
>>>>> PNG file
>>>>>   res                     = True
>>>>>   res at gsnDraw           = False         ; Don't draw plots
>>>>>   res at gsnFrame          = False         ; Don't advance frame
>>>>>   res at cnFillOn          = True          ; Turn on contour fill
>>>>>   res at cnLinesOn         = False         ; Turn off contour lines
>>>>>   res at cnFillPalette       = "MPL_YlOrRd"   ; set color map
>>>>>   res at tiMainString        = "Overlaying shaded contours on filled
>>>>> contours"
>>>>> ;  res at cnFillMode = "RasterFill"
>>>>>   res at cnLevelSelectionMode =  "ManualLevels"
>>>>>   res at cnMinLevelValF       = 0.0
>>>>>   res at cnMaxLevelValF       = 5.0
>>>>>   res at cnLevelSpacingF      = 0.5
>>>>>
>>>>> ;   res at gsnAddCyclic     = False
>>>>>    res at mpMinLatF    =   -10.0               ; only plot 30S to 30N
>>>>>    res at mpMaxLatF    =  54.0
>>>>>    res at mpMinLonF    = 30.0              ; only plot 30S to 30N
>>>>>    res at mpMaxLonF    = 100.0
>>>>>
>>>>>   plot = gsn_csm_contour_map(wks,rain,res)
>>>>>
>>>>>   opt = True
>>>>>   opt at gsnShadeFillType = "pattern"      ; pattern fill
>>>>>   opt at gsnShadeHigh = 2                  ; use pattern #2
>>>>>   opt at gsnShadeLow = 17                  ; use pattern #17
>>>>>   plot2 = gsn_contour_shade(plot,0.5,3.0,opt)
>>>>>   overlay(plot,plot2)
>>>>>
>>>>>   draw(plot)
>>>>>   frame(wks)
>>>>> end
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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