Re: coloring vectors using a scalar

Hi Nicole,

I think you're almost there. The ***FieldData and sfDataArray
resources should not be set by you. These are being set internally by
the gsn_csm_vector_xxx routine.
Also, you don't need to set vcUseScalarArray, as this is set
internally when you call gsn_csm_vector_scalar_map.

By default, the gsn_csm_vector_scalar_map routine should be coloring
your vectors according to the given scalar field.

I've attached a sample script and PNG image to show this. Please let
me know if you are not seeing the same results.

--Mary




On Nov 13, 2009, at 7:32 PM, Nicole Schiffer wrote:

> I'm trying to color vectors using a scalar with the
> gsn_csm_vector_scalar_map function. My understanding is that this
> should be the default behavior, but the vectors are still colored
> by magnitude. I've included a code snippet below. Commented code
> are options that I have tried in various combinations. Thanks.
>
> ; Open a workspace to begin creating the plot
> wsplot = gsn_open_wks("ps", "./graphs/anomavgNARR."+filemidout
> +"."+i)
>
> ; Change options for plot (res=True)
> res = True
>
> ; Color fill on, contours off, line labels off, manual level
> selection
> ; mode, spacing every 1.0 units, min value 270, max value 320, use
> ; entire color spectrum
> res@gsnSpreadColors = True
>
> ; set vector resources
> res@vfXCStride = 4
> res@vfYCStride = 4
> res@vcRefMagnitudeF = 100000.0
> res@vcRefLengthF = 0.008
> res@vcGlyphStyle = "LineArrow"
> res@vcRefAnnoOrthogonalPosF = -1.0
> res@vcRefAnnoParallelPosF = 1.0
> res@vcLineArrowThicknessF = 3.0
> res@vcVectorDrawOrder = "PostDraw"
> res@vcMapDirection = False
>
> ;res@sfDataArray = vectorcolor
> ;res@vcLevelSelectionMode = "ExplicitLevels"
> res@vcScalarFieldData = vectorcolor
> ;res@vcVectorFieldData =
> res@vcMonoLineArrowColor = False
> ;res@sfMissingValueV = -999
> res@vcScalarMissingValColor = -1
> res@vcUseScalarArray = True
> ;res@vcLevelColors = (/0,1,2,3/)
> ;res@vcLevels = (/-0.5,0,0.5/)
> ;res@vcLevelCount = 3
>
> ; Draw map boundaries: coastlines, national boundaries, and
> states/provinces
> res@mpAreaMaskingOn = False
> res@mpFillOn = False
> res@mpDataBaseVersion="Ncarg4_1"
> res@mpOutlineBoundarySets = "National"
> res@mpOutlineSpecifiers = (/"Canada:Provinces", "United
> States:States", "Mexico:States"/)
>
> ; Always display tick marks
> res@pmTickMarkDisplayMode = "Always"
> ; Do not add cyclic reference point, maximize plot to workstation
> size,
> ; orient paper horizontally, 0.5 inch paper margin
> res@gsnAddCyclic = False
> res@gsnMaximize = True
> res@gsnPaperOrientation = "landscape"
> res@gsnPaperMargin = 0.5
> ; blank strings above image
> res@gsnCenterString = ""
> res@gsnRightString = ""
> res@gsnLeftString = ""
> res@gsnScalarContour = False
>
> ; Define map projection properties
> res@mpProjection = "LambertConformal"
> res@mpLambertMeridianF = 253
> res@mpLambertParallel1F = 50
> res@mpLambertParallel2F = 50
>
> ; Define display boundaries
> res@mpLimitMode = "Corners"
> res@mpLeftCornerLatF = lat2d(0,nlat/6)
> res@mpLeftCornerLonF = lon2d(0,nlat/6)
> res@mpRightCornerLatF = lat2d(mlon/2,nlat-nlat/3)
> res@mpRightCornerLonF = lon2d(mlon/2,nlat-nlat/3)
> ; map perimeter on, map fill on, no map rotation
> res@mpPerimOn = True
> res@mpCenterRotF = 0
> ; 10deg lat-lon grid spacing, show lat-lon grid, make lat-lon lines
> ; dashed
> res@mpGridSpacingF = 10.0
> res@mpGridAndLimbOn = True
> res@mpGridLineDashPattern = 16
> ; NCDOverlay is false
> res@tfDoNDCOverlay = False
>
> ; Create the label bar for the colored contours
> res@lbLabelFontHeightF = 0.020
> res@lbTitleString = ""
> res@lbLabelFont = 21
> res@lbLabelAutoStride = False
> res@lbLabelStride = 10
> res@lbOrientation = "Vertical"
> res@pmLabelBarOrthogonalPosF = 0.02
> res@pmLabelZone = 2
> res@lbBoxLinesOn = True
>
> ; Define the colorscale for the plot and reverse it (R-W-B)
> gsn_define_colormap(wsplot, "cosam")
>
> ; Create the plot
> plot = gsn_csm_vector_scalar_map(wsplot, plotthisu(:,:), plotthisv
> (:,:), vectorcolor(:,:), res)
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> * Nicole Schiffer
> * Graduate Research Assistant
> * Department of Atmospheric Sciences
> * University of Illinois, Urbana-Champaign
> * Email: nschiff2 [at] illinois [dot] edu
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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> ncl-talk mailing list
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Received on Sun Nov 15 20:12:35 2009