NhlDataToNDC (datatondc)

Converts data units into normalized device coordinates (NDCs). (See NhlDataToNDC.) Two names are provided for this NCL procedure: the formal name is NhlDataToNDC, and the abbreviated name is datatondc.

Synopsis

	procedure NhlDataToNDC(
		plot[1] : graphic,
		x_in[*] : float,
		y_in[*] : float,
		x_out[*] : float,
		y_out[*] : float
	)

	or

	procedure datatondc(
                plot[1] : graphic,
                x_in[*] : float,
                y_in[*] : float,
                x_out[*] : float,
                y_out[*] : float
        )

Arguments

plot

HLU plot.

x_in

Single-dimensioned floating-point vector of x data coordinates.

y_in

Single-dimensioned floating-point vector of y data coordinates; must be the same size as x_in.

x_out

Single-dimensioned floating-point vector the same size as x_in; will contain x-coordinate output for datatondc.

y_out

Single-dimensioned floating-point vector the same size as x_out; will contain y-coordinate output from datatondc.

Description

The NhlDataToNDC procedure uses the built-in transformation mapping feature of HLU plot objects to map data coordinates into Normalized Device Coordinates (screen coordinates). All four floating-point parameters must have the same number of elements. NhlDataToNDC maps coordinate pairs from x_in and y_in and places the results in the corresponding elements of x_out and y_out respectively. Both x_out and y_out can be the same variables as x_in and y_in. When the data coordinates are outside of the data transformation specified in the plot, a missing value is placed in both of the corresponding indexes in the output arrays. The missing value chosen is either the x_in missing value, y_in missing value, or a system default.

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$Revision: 1.10 $ $Date: 1998/09/17 16:10:44 $