2D Interpolation

Overview

The 2D interpolation module provides some methods to load 2D tables of data and computing values by interpolating. It only works for data provided in a rectangular grid.

interp2d.new(x, y, z[, options])

Creates a new Interp2D object based on the provided data. x and y must be vectors containing the x and y values of the cartesian grid where the data lies. z must be a matrix containing the data to be interpolated. To be acceptable the vectors and matrix x, y and z must have respectively dimensions N, M and N x M.

The optional argument options can provide the field type to be a string between “linear” and “cubic” to choose the kind of interpolation. It can also provide the field extrapolate to a boolean that indicate if extrapolation outside of the domain is allowed. The extrapolate option is set to true by default.

interp2d.new_from_csv(filename[, options])

Create a new Interp2D object based on a csv file. The data should be arranged in the following way:

0      x1     x2     x3     ...     xn
y1     z11    z21    z31    ...     zn1
y2     z12    z22    z32    ...     zn2
y3     z13    z23    z33    ...     zn3
...    ...    ...    ...    ...     ...
ym     z1m    z2n    z3n    ...     znn

The first cell in the table can be set to any value or left empty as it is not used.

The options optional arguments is the same than for the interp2d.new() function.

interp2d.read_csv(filename)

Read a csv file formatted like for the function new_from_csv() and returns the vectors and matrix x, y and z.

2D Interpolation class

class interp2d.Interp2D

eval(x, y)

Returns the interpolated value for the given x and y values.

eval_deriv(x, y)

Returns the interpolated derivatives with respect to x and y respectively for the given x and y values.