bicubic.grid | R Documentation |
This is a placeholder function for backward compatibility with packaga akima.
In its current state it simply calls the reimplemented Akima algorithm for irregular grids applied to the regular gridded data given.
Later a reimplementation of the original algorithm for regular grids may follow.
bicubic.grid(x,y,z,xlim=c(min(x),max(x)),ylim=c(min(y),max(y)),
nx=40,ny=40,dx=NULL,dy=NULL)
x |
a vector containing the |
y |
a vector containing the |
z |
a matrix containing the |
xlim |
vector of length 2 giving lower and upper limit for range |
ylim |
vector of length 2 giving lower and upper limit for range of |
nx |
output grid dimension in |
ny |
output grid dimension in |
dx |
output grid spacing in |
dy |
output grid spacing in |
This function is a call wrapper for backward compatibility with package akima.
Currently it applies Akimas irregular grid splines to regular grids, later a FOSS reimplementation of his regular grid splines may replace this wrapper.
This function produces a grid of interpolated points, feasible to be
used directly with image
and contour
:
x |
vector of |
y |
vector of |
z |
matrix of interpolated data for the output grid. |
Use interp
for the general case of irregular gridded data!
Akima, H. (1996) Rectangular-Grid-Data Surface Fitting that Has the Accuracy of a Bicubic Polynomial, J. ACM 22(3), 357-361
interp
, bicubic
data(akima474)
# interpolate at a grid [0,8]x[0,10]
akima.bic <- bicubic.grid(akima474$x,akima474$y,akima474$z)
zmin <- min(akima.bic$z, na.rm=TRUE)
zmax <- max(akima.bic$z, na.rm=TRUE)
breaks <- pretty(c(zmin,zmax),10)
colors <- heat.colors(length(breaks)-1)
image(akima.bic, breaks=breaks, col=colors)
contour(akima.bic, levels=breaks, add=TRUE)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.