[ncl-talk] Can i set the opacity of each color ??
Kyle Griffin
ksgriffin2 at wisc.edu
Fri Aug 29 16:20:32 MDT 2014
Hi Mary,
Thanks for the clarification. I think Rabah would need to use cnFillPalette
as it seems like he has multiple opacities to set that vary by color. On a
related note, is it possible to readily change cnFillOpacityF to accept an
array of values, much like setting cnFillColors allows one to set RGB/RGBA
colors? This would allow for a more readily accessible method of setting
varying opacities rather than via direct manipulation of the color
quadruplets. Just a suggestion, as I've generally struggled in my attempts
to make alpha values work from a color table file.
Kyle
----------------------------------------
Kyle S. Griffin
Department of Atmospheric and Oceanic Sciences
University of Wisconsin - Madison
Room 1421
1225 W Dayton St, Madison, WI 53706
Email: ksgriffin2 at wisc.edu
On Fri, Aug 29, 2014 at 4:22 PM, Mary Haley <haley at ucar.edu> wrote:
> Hi Kyle and Rabah,
>
> Sorry about the confusion on gsn_define_colormap. It doesn't seem to
> handle RGBA type color maps, although you can certainly set a colormap
> using gsn_define_colormap, and then apply opacity to it later via opacity
> resources like cnFillOpacityF
>
> We recommend using "cnFillPalette" if you want to use a color map that has
> various opacity values set.
>
> See the attached example, which you should be able to run as-is. It shows
> two ways to set opacities.
>
> I'm not sure what's going on with the labelbar, and whether this is
> correct. Rick will need to weigh in here.
>
> --Mary
>
>
>
> On Thu, Aug 28, 2014 at 9:32 PM, Kyle Griffin <ksgriffin2 at wisc.edu> wrote:
>
>> Hi Rabah,
>>
>> As far as I know, gsn_define_colormap does not support RGBA colors, but I
>> can't immediately find that in the documentation. If you want to use all of
>> the colors in your color array, directly assign res at cnFillColors =
>> colors (or colors(:,0:2) if you only want the first three colors) and this
>> will set all of the colors in that array to be used in the FillColors.
>> However, I believe the "more proper" way is to use cnFillPalette, as
>> specified in the link I sent you in the last email.
>>
>>
>> Kyle
>>
>> ----------------------------------------
>> Kyle S. Griffin
>> Department of Atmospheric and Oceanic Sciences
>> University of Wisconsin - Madison
>> Room 1421
>> 1225 W Dayton St, Madison, WI 53706
>> Email: ksgriffin2 at wisc.edu
>>
>>
>> On Thu, Aug 28, 2014 at 10:17 PM, Rabah Hachelaf <hachelaf at sca.uqam.ca>
>> wrote:
>>
>>> Hi Kyle,
>>>
>>> I think your suggestion doesn't work because when i add the 4th values
>>> for opacity i get this message ;
>>> (0) Warning: gsn_define_colormap: cmap must either be an n x 3 float
>>> array,
>>> (0) a single pre-defined colormap name, or a 1-dimensional string
>>> array of named colors.
>>>
>>> i simplified my script like this :
>>>
>>> colors = (/ (/255,255,255,1/), (/163,255,163,125/), (/255,178,102,200/)
>>> /) * 1.0
>>> colors= colors/255.
>>> print(colors)
>>>
>>> gsn_define_colormap(wks,colors)
>>> ......
>>> ......
>>> .........
>>> res at cnLevelSelectionMode = "ExplicitLevels" ; set explicit contour
>>> levels
>>> res at cnLevels = (/ 40,70,100/) ; set levels
>>> res at cnFillColors = (/ 0,1,2/)
>>>
>>>
>>>
>>>
>>>
>>> 2014-08-28 22:42 GMT-04:00 Kyle Griffin <ksgriffin2 at wisc.edu>:
>>>
>>> You should be able to just add a fourth value to your RGB triplets to
>>>> make them RGBA (A for alpha) quadruplets. Since you already divide the
>>>> numbers out of 255, you can simply add the alpha on the same scale, with 0
>>>> = transparent and 1=opaque (or 255, in your case).
>>>>
>>>> More of the problem is that you don't seem to be assigning the color
>>>> array you create at the beginning of the script to the cnFillColors
>>>> resource you set later on. Look at some of the examples on the NCL website
>>>> discussing how to work with the new color capabilities at:
>>>> http://www.ncl.ucar.edu/Applications/rgbacolor.shtml
>>>>
>>>>
>>>> Kyle
>>>>
>>>> ----------------------------------------
>>>> Kyle S. Griffin
>>>> Department of Atmospheric and Oceanic Sciences
>>>> University of Wisconsin - Madison
>>>> Room 1421
>>>> 1225 W Dayton St, Madison, WI 53706
>>>> Email: ksgriffin2 at wisc.edu
>>>>
>>>>
>>>> On Thu, Aug 28, 2014 at 8:44 PM, Rabah Hachelaf <hachelaf at sca.uqam.ca>
>>>> wrote:
>>>>
>>>>>
>>>>> Hi all ,
>>>>>
>>>>> I am using the script below to plot humidity between 40-70%(green) and
>>>>> 70-100% (orange).
>>>>>
>>>>> I want to know if i can set the opacity for each color for example
>>>>> opacity 50% for the green color and 100% for the orange.
>>>>>
>>>>> Thanks for help.
>>>>>
>>>>> ;************************************************
>>>>> 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"
>>>>> ;************************************************
>>>>> begin
>>>>> a = addfile("gfs.t00z.pgrb2f00.grib2","r")
>>>>> lon = a->lon_0
>>>>> lat = a->lat_0
>>>>> icing = short2flt(a->RH_P0_L100_GLL0({50000},:,:))
>>>>>
>>>>> print(icing(1:4,1:4))
>>>>> ;********************************************************
>>>>> ; Display parameters
>>>>> ;***************************************
>>>>> zoom="test"
>>>>> pixel=2048
>>>>> ;***************************************************
>>>>>
>>>>> wks_type="png"
>>>>>
>>>>> wks_type at wkWidth = pixel
>>>>> wks_type at wkHeight = pixel
>>>>> wks_type at wkBackgroundOpacityF = 0.0
>>>>> wks = gsn_open_wks(wks_type,"icing_test")
>>>>>
>>>>> colors = (/ (/255,255,255/),(/0,0,0/),(/255,255,255/),
>>>>> (/244,255,244/), \
>>>>> (/217,255,217/), (/163,255,163/), (/106,255,106/), \
>>>>> (/43,255,106/), (/0,224,0/), (/0,134,0/),(/255,145,0/),\
>>>>> (/255,178,102/) /) * 1.0 ; we multiply by 1 to make
>>>>> colors float
>>>>>
>>>>> colors = colors/255.
>>>>>
>>>>>
>>>>> gsn_define_colormap(wks,colors)
>>>>>
>>>>>
>>>>> res = True
>>>>> res at mpProjection = "Mercator" ; choose projection
>>>>> res at mpGridAndLimbOn = False ; turn on lat/lon lines
>>>>> res at mpPerimOn = False ; turn off box around plot
>>>>> res at mpFillOn = False
>>>>> res at mpOutlineOn = True
>>>>> res at cnFillOn = True ; color plot desired
>>>>> res at cnLineLabelsOn = False ; turn off contour lines
>>>>> res at mpLimitMode = "LatLon"
>>>>> res at mpMinLatF = -85.0
>>>>> res at mpMaxLatF = 85.0
>>>>> res at mpMinLonF = -180
>>>>> res at mpMaxLonF = 180
>>>>> res at vpXF = 0 ; make plot bigger
>>>>> res at vpYF = 1
>>>>> res at vpWidthF = 1
>>>>> res at vpHeightF = 1
>>>>>
>>>>> res at cnLevelSelectionMode = "ExplicitLevels" ; set explicit contour
>>>>> levels
>>>>> res at cnLevels = (/ 40,70,100/) ; set levels
>>>>> res at cnFillColors = (/ -1,5,11/)
>>>>>
>>>>> ;res at cnFillOpacityF=0.5
>>>>>
>>>>> contour0 = gsn_csm_contour_map(wks,icing,res) ; create the plot
>>>>> --
>>>>> ------------------------------
>>>>> Cordialement,
>>>>> Best regards,
>>>>> Rabah Hachelaf
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> ------------------------------
>>>>> Cordialement,
>>>>> Best regards,
>>>>> Rabah Hachelaf
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
>>>>> List instructions, subscriber options, unsubscribe:
>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> ------------------------------
>>> Cordialement,
>>> Best regards,
>>> Rabah Hachelaf
>>>
>>
>>
>> _______________________________________________
>> ncl-talk mailing list
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>>
>
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