NCL Home > Documentation > Graphics > Graphical Interfaces

gsn_vector_scalar_map

Creates and draws a vector plot over a map, and colors the vectors using the given scalar field.

Prototype

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"  ; This library is automatically loaded
                                                          ; from NCL V6.2.0 onward.
                                                          ; No need for user to explicitly load.

	function gsn_vector_scalar_map (
		wks     [1] : graphic,  
		u    [*][*] : numeric,  
		v    [*][*] : numeric,  
		data [*][*] : numeric,  
		res     [1] : logical   
	)

	return_val [1] :  graphic

Arguments

wks

A Workstation identifier. The identifier is one returned either from calling gsn_open_wks or calling create to create a Workstation object.

u
v

The u and v data for the vector plot; must be two-dimensional.

data

The data for which to color the vectors by; must be two-dimensional.

res

A variable containing an optional list of plot resources, attached as attributes. Set to True if you want the attached attributes to be applied, and False if you either don't have any resources to set, or you don't want the resources applied.

Return value

A scalar id of the map plot created is returned. The id of the vector plot is returned as an attribute called vector. The id of the data object is returned as an attribute called vfdata, and the id of the scalar data object is returned as an attribute called sfdata. This is useful if you want to use setvalues to change some data options after this function has been called.

Description

This function creates and draws a vector plot over a map on the given workstation, and colors the vectors given a scalar field. If u, v, or data have a _FillValue attribute, these values will be used as missing values.

You should use gsn_csm_vector_scalar_map if you want a more customized vector plot, if you want the scalar field to be represented as a separate contour plot, and/or if any of your data has coordinate arrays. To maximize the area that the vector plot is drawn in, set the special resource gsnMaximize to True.

Examples

For some application examples, see:

"gsn_vec_scal_3.ncl" (view example)