Class interp2_neigh (o2scl)¶
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template<class vec_t>
class interp2_neigh¶ Nearest-neighbor interpolation in two dimensions.
This class performs nearest-neighbor interpolation when the data points are not arranged in a specified order (i.e. not on a grid). For a set of data \( {x_i,y_i,f_i} \), the value of \( f \) is predicted given a new value of x and y. Distances are determined with
\[ d_{ij} = \sqrt{\left(\frac{x_i-x_j}{\Delta x}\right)^2 + \left(\frac{y_i-y_j}{\Delta y}\right)^2} \]The values \( \Delta_x \) and \( \Delta_y \) are specified in x_scale and y_scale, respectively. If these values are negative (the default) then they are computed with \( \Delta x = x_{\mathrm{max}}-x_{\mathrm{min}} \) and \( \Delta y = y_{\mathrm{max}}-y_{\mathrm{min}} \) .This class stores pointers to the data, not a copy. The data can be changed between interpolations without an additional call to set_data(), but the scales may need to be recomputed with compute_scale().
The vector type can be any type with a suitably defined
operator[].- Idea for Future:
Maybe interpm_idw subsumes this functionality and makes this class obsolete? Or is this specialization particularly efficient?
Note
This class operates by performing a \( {\cal O}(N) \) brute-force search to find the closest points.
Public Types
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typedef boost::numeric::ublas::vector<double> ubvector¶
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typedef boost::numeric::ublas::vector<size_t> ubvector_size_t¶
Public Functions
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inline interp2_neigh()¶
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inline void compute_scale()¶
Find scaling.
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inline void set_data(size_t n_points, vec_t &x, vec_t &y, vec_t &f)¶
Initialize the data for the neigh interpolation.
This function will call the error handler if
n_pointsis zero.
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inline double eval(double x, double y) const¶
Perform the interpolation.
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inline double operator()(double x, double y) const¶
Perform the interpolation.
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template<class vec2_t>
inline double operator()(vec2_t &v) const¶ Perform the interpolation using the first two elements of
vas input.
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inline void eval_point(double x, double y, double &f, size_t &i1, double &x1, double &y1) const¶
Interpolation returning the closest point.
This function interpolates
xandyinto the data returningf. It also returns the closest x- and y-values found.