Re: position of the value 0 in cnLevels to be represented by white colour.

On 10 March 2011 10:09, gibies george <gibies@tropmet.res.in> wrote:

> Thank you Mary,
>
> This is exactly what I was looking for.
>
>
But the script

  plot(ptn) = gsn_csm_contour_map(wkspnl,\
data({region@latsouth:region@latnorth},{region@lonwest:region@loneast
},j,pos),resc)
;---Retrieve contour levels
  getvalues plot(ptn)
    "cnLevels" : levels ;;;; Here is line 1968 in file script1.ncl
  end getvalues

  nlevels = dimsizes(levels)

shows an error :

*warning:gsnScalarContour is not a valid resource in
rain_tropics_dem_ecmwf_Climatology_contour at this time*
*warning:cnLevels is not a valid resource in map at this time*
*warning:NhlGetValues:Error retrieving cnLevels*
*fatal:Execute: Error occurred at or near line 1968 in file script1.ncl*

> On 10 March 2011 01:28, Mary Haley <haley@ucar.edu> wrote:
>
>> Gibies,
>>
>> Instead of using gsnSpreadXXXX, you will probably need to set the
>> cnFillColors resource to an array of color indexes, so you can control which
>> contour level gets which color index.
>>
>> If you are setting the contour levels yourself, then you should be able to
>> determine what to set cnFillColors to.
>>
>> If you are letting NCL select the contour levels, then you will need to
>> let NCL create the plot, and thn afterwards use "getvalues" to retrieve the
>> "cnLevels" resource and construct cnFillColors based on those values.
>>
>> Something like this:
>>
>> . . .
>> plot = gsn_csm_contour_map(wks,data,res)
>>
>> ;---Retrieve contour levels
>> getvalues plot
>> "cnLevels" : levels
>> end getvalues
>>
>> nlevels = dimsizes(levels)
>>
>> ;---Create array containing fill indexes.
>> colors = new(nlevels+1,integer)
>> ii = ind(levels.ge.0)
>> num_neg = ii(0)
>> num_pos = nlevels-num_neg+1
>>
>> colors(0:num_neg-1) = ispan(2,51,toint(51/(num_neg-1)))
>> colors(num_neg:) = ispan(53,103,toint(51/(num_pos-1)))
>>
>> res@cnFillColors= colors
>> plot = gsn_csm_contour_map(wks,data,res)
>>
>>
>>
>> You will need to modify this based on whether you have a contour level
>> exactly equal to 0 or not.
>>
>> --Mary
>>
>>
>> On Mar 9, 2011, at 3:51 AM, gibies george wrote:
>>
>> Thank you Mary for the response.
>>
>> I am using *gsn_csm_contour_map* with "*ViBlGrWhYeOrRe*" colour-map
>>
>> I wish to have :
>>
>> the colours from 1 to 51 ie "*ViBlGr" to be used for negative values.*
>> *the colour 52 ie "White" to be used for zero.*
>> *the colours from 53 to 103 ie "YeOrRe" to be used for positive values.*
>> *
>> *
>> I tried to manage it using *gsnSpreadColorStart *and *gsnSpreadColorEnd*in the cases when (data_min
>> .gt. 0) or (data_max .lt. 0) but I don't know how to handle the case when
>> *(**data_min .lt. 0**) .and. (data_max .gt. 0) which i really want. *
>>
>> I am afraid that I may not get full range of color map while
>> using "gsn_contour_shade"
>>
>>
>> On 9 March 2011 03:57, Mary Haley <haley@ucar.edu> wrote:
>>
>>> Maybe "gsn_contour_shade" is what you're looking for:
>>>
>>>
>>> http://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_contour_shade.shtml
>>>
>>
>>
>>
>>
>>> --Mary
>>>
>>> On Mar 8, 2011, at 5:47 AM, gibies george wrote:
>>>
>>> How can I get the position of the value 0 in cnLevels while setting the
>>> resources for contour plot ?
>>>
>>> My requirement is as follows.
>>>
>>> I would like to get *white to represent the value near to zero* in
>>> contour interval irrespective of the data range.
>>> ---------
>>> ----------
>>> -----------
>>>
>>> gsn_define_colormap(wkspnl,"ViBlGrWhYeOrRe")
>>> white = 52
>>> data_min = min(data)
>>> data_max = max(data)
>>>
>>> if (data_min .gt. 0) resc@gsnSpreadColorStart = white
>>> resc@cnLevelSelectionMode = "ManualLevels" resc@cnMinLevelValF = 0 end
>>> if if (data_max .lt. 0) resc@gsnSpreadColorEnd = white
>>> resc@cnLevelSelectionMode = "ManualLevels" resc@cnMaxLevelValF = 0 end
>>> if
>>>
>>> if ((data_min .lt. 0) .and. (data_max .gt. 0))
>>> *----------*
>>> *???????*
>>> *----------* end if
>>> ----------------------
>>> -----------------------
>>> ----------------------
>>>
>>> How can I implement this?
>>>
>>>
>>> --
>>> *Gibies George, CSIR-RF,*
>>> *Seasonal Scale Prediction Group,
>>> Climate and Global Modelling Division,
>>> Indian Institute of Tropical Meteorology,
>>> Dr. Homi Bhabha Road,
>>> NCL (P. O.), Pashan,
>>> Pune 411008, India.*
>>>
>>> *http://sites.google.com/site/gibiesge/*
>>>
>>> Please Think about the environment. Save paper; Save Trees; and don't
>>> print this e-mail unless it is necessary.
>>> _______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
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>>>
>>>
>>>
>>
>>
>> --
>> *Gibies George, CSIR-RF,*
>> *Seasonal Scale Prediction Group,
>> Climate and Global Modelling Division,
>> Indian Institute of Tropical Meteorology,
>> Dr. Homi Bhabha Road,
>> NCL (P. O.), Pashan,
>> Pune 411008, India.*
>>
>> *http://sites.google.com/site/gibiesge/*
>>
>> Please Think about the environment. Save paper; Save Trees; and don't
>> print this e-mail unless it is necessary.
>> _______________________________________________
>> ncl-talk mailing list
>> List instructions, subscriber options, unsubscribe:
>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>>
>>
>
>
> --
> *Gibies George, CSIR-RF,*
> *Seasonal Scale Prediction Group,
> Climate and Global Modelling Division,
> Indian Institute of Tropical Meteorology,
> Dr. Homi Bhabha Road,
> NCL (P. O.), Pashan,
> Pune 411008, India.*
>
> *http://sites.google.com/site/gibiesge/*
>
> Please Think about the environment. Save paper; Save Trees; and don't print
> this e-mail unless it is necessary.
>

-- 
*Gibies George,   CSIR-RF,*
*Seasonal Scale Prediction Group,
Climate and Global Modelling Division,
Indian Institute of Tropical Meteorology,
Dr. Homi Bhabha Road,
NCL (P. O.), Pashan,
Pune 411008, India.*
*http://sites.google.com/site/gibiesge/*
Please Think about the environment. Save paper; Save Trees; and don't print
this e-mail unless it is necessary.