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nnpnts

Interpolates from 2D random float data to get values at a specified set of points. (Deprecated version.)

Prototype

	function nnpnts (
		x [*] : float,  
		y [*] : float   
	)

	return_val [dimsizes(x)] :  double

Arguments

x

An array of X coordinates of points where interpolation is desired, of length npts.

y

An array of Y coordinates of points where interpolation is desired, of length npts.

Return value

An array, of the same size as x and y, containing interpolated function values.

Description

[Deprecated: use nnpnt instead.]

This function is part of the Natgrid package, which implements a natural neighbor interpolation method. Much useful information is available at the above link, including the descriptions of many control parameters that can be modified to materially change its behavior. (The functions nngetp and nnsetp are used to access these parameters.)

nnpnts interpolates to get function values at specified points. It may only be called after calling nnpntinit, nnpntinits, or nnpntinitd.

nnpntinit and nnpnt are "generic" functions that accept any type of numeric input, nnpntinits and nnpnts require input of type float, and nnpntinitd and nnpntd require input of type double. However, each of these references the same internal structure, so it is possible to use one form for the initialization and another form for the actual interpolation.

See Also

nnpnt

Examples

begin
  NUMXOUT = 21
  NUMYOUT = 21
;
;  Coordinate data are defined as random numbers between -0.2
;  and 1.2 and are explicitly defined here for uniformity
;  across platforms.
; 
  x = (/                                                        \
  1.16,  0.47,  0.29,  0.72,  0.52,  1.12,  0.33,  0.20,  0.30, \
  0.78,  0.92,  0.52,  0.44,  0.22, -0.10,  0.11,  0.59,  1.13, \
  0.68,  1.11,  0.93,  0.29,  0.74,  0.43,  0.87,  0.87, -0.10, \
  0.26,  0.85,  0.00, -0.02,  1.01, -0.12,  0.65,  0.39,  0.96, \
  0.39,  0.38,  0.94, -0.03, -0.17,  0.00,  0.03,  0.67, -0.06, \
  0.82, -0.03,  1.08,  0.37,  1.02, -0.11, -0.13,  1.03,  0.61, \
  0.26,  0.18,  0.62,  0.42,  1.03,  0.72,  0.97,  0.08,  1.18, \
  0.00,  0.69,  0.10,  0.80,  0.06,  0.82,  0.20,  0.46,  0.37, \
  1.16,  0.93,  1.09,  0.96,  1.00,  0.80,  0.01,  0.12,  1.01, \
  0.48,  0.79,  0.04,  0.42,  0.48, -0.18,  1.16,  0.85,  0.97, \
  0.14,  0.40,  0.78,  1.12,  1.19,  0.68,  0.65,  0.41,  0.90, \
  0.84, -0.11, -0.01, -0.02, -0.10,  1.04,  0.58,  0.61,  0.12, \
 -0.02, -0.03,  0.27,  1.17,  1.02,  0.16, -0.17,  1.03,  0.13, \
  0.04, -0.03,  0.15,  0.00, -0.01,  0.91,  1.20,  0.54, -0.14, \
  1.03,  0.93,  0.42,  0.36, -0.10,  0.57,  0.22,  0.74,  1.15, \
  0.40,  0.82,  0.96,  1.09,  0.42,  1.13,  0.24,  0.51,  0.60, \
  0.06,  0.38,  0.15,  0.59,  0.76,  1.16,  0.02,  0.86,  1.14, \
  0.37,  0.38,  0.26,  0.26,  0.07,  0.87,  0.90,  0.83,  0.09, \
  0.03,  0.56, -0.19,  0.51,  1.07, -0.13,  0.99,  0.84,  0.22 /)

  y = (/                                                        \
 -0.11,  1.07,  1.11, -0.17,  0.08,  0.09,  0.91,  0.17, -0.02, \
  0.83,  1.08,  0.87,  0.46,  0.66,  0.50, -0.14,  0.78,  1.08, \
  0.65,  0.00,  1.03,  0.06,  0.69, -0.16,  0.02,  0.59,  0.19, \
  0.54,  0.68,  0.95,  0.30,  0.77,  0.94,  0.76,  0.56,  0.12, \
  0.05, -0.07,  1.01,  0.61,  1.04, -0.07,  0.46,  1.07,  0.87, \
  0.11,  0.63,  0.06,  0.53,  0.95,  0.78,  0.48,  0.45,  0.77, \
  0.78,  0.29,  0.38,  0.85, -0.10,  1.17,  0.35,  1.14, -0.04, \
  0.34, -0.18,  0.78,  0.17,  0.63,  0.88, -0.12,  0.58, -0.12, \
  1.00,  0.99,  0.45,  0.86, -0.15,  0.97,  0.99,  0.90,  0.42, \
  0.61,  0.74,  0.41,  0.44,  1.08,  1.06,  1.18,  0.89,  0.74, \
  0.74, -0.06,  0.00,  0.99,  0.03,  1.00, -0.04,  0.24,  0.65, \
  0.12,  0.13, -0.09, -0.05,  1.03,  1.07, -0.02,  1.18,  0.19, \
  0.03, -0.03,  0.86,  1.12,  0.38,  0.72, -0.20, -0.08, -0.18, \
  0.32,  0.13, -0.19,  0.93,  0.81,  0.31,  1.09, -0.03,  1.01, \
 -0.17,  0.84, -0.11,  0.45,  0.18,  0.23,  0.81,  0.39,  1.09, \
 -0.05,  0.58,  0.53,  0.96,  0.43,  0.48,  0.96, -0.03,  1.13, \
  1.16,  0.16,  1.15,  0.57,  0.13,  0.71,  0.35,  1.04,  0.62, \
  1.03,  0.98,  0.31,  0.70,  0.97,  0.87,  1.14,  0.08,  1.19, \
  0.88,  1.00,  0.51,  0.03,  0.17,  1.01,  0.44,  0.17, -0.11 /)

  z = (x-0.25)*(x-0.25) + (y-0.50)*(y-0.50)

  xc = 1./(NUMXOUT-1.) 
  xo = ispan(0,NUMXOUT-1,1) * xc

  yc = 1./(NUMYOUT-1.)
  yo = ispan(0,NUMYOUT-1,1) * yc

;
; 2D representations of xo and yo.
;
  xo2d_1   = onedtond(xo,(/NUMYOUT,NUMXOUT/))
  yo2d     = onedtond(yo,(/NUMXOUT,NUMYOUT/))
  xo2d_1!0 = "y"
  xo2d_1!1 = "x"
  xo2d     = xo2d_1(x|:,y|:)

  nnpntinits(x,y,z)
  zo1d = nnpnts(ndtooned(xo2d),ndtooned(yo2d))   ; Interpolate.
  zo2d = onedtond(zo1d,(/NUMXOUT,NUMYOUT/))      ; Convert to 2D.
  nnpntend()                                     ; Clean up.
end