How to Use It?

[jamiejackson]

I can't find much documentation on this and the README is both bare-bones and pretty opaque. A real-world use case would help.

The following is my naive attempt. I know it's wrong but it will be useful to show what I need. Also note that the grid spacing of the known data is not even. (By the way, here is my working example using python.)

I am also interested in extrapolating values outside of the known data bounds. Is the ndarray-linar-interpolate library capable of that?

var ndarray = require("ndarray");
var interp = require("ndarray-linear-interpolate");

// Create the 2D ndarray object from the given data
// The first column is "diameter in inches" and the first row is "psi"
// The first cell (A:1)is a dummy value
var data = ndarray(new Float32Array([
  0, 60, 120, 240, 360, 480,
  4, 71, 100, 142, 173, 200,
  6, 106, 150, 212, 260, 300,
  8, 142, 200, 283, 347, 400 ,
  10, 177, 250, 354, 433, 500,
  12, 212, 300, 425, 520, 601,
  14,  248, 350, 495, 607, 701,
  16,  283, 400, 566, 693, 801,
  18,  318, 450, 637, 780, 901,
  20,  354, 500, 708, 867, 1001,
  22,  389, 550, 779, 953, 1101
]), [10,6]);

console.log(interp(data, 4.1, 61)); // x=4.1 inches, y=61 psi. expect a value of a little over 72 but it returns 0.

[jamiejackson]

Soon after I posted, I bailed and went with Python / scipy / RegularGridInterpolator, which was documented, relatively easy to work with, and supported extrapolation outside of known data.