Get Surface

Get Two-Dimensional Control Net and Surface from n-dimensional Control Nets

Usage

get_surface(x, margin = 1:2, at, n = 100)

Arguments

x

a cpr_cn object

margin

an integer identifying the marginal of the control net to slice along. Only used when working x is a cpr_cn object.

at

point value for marginals not defined in the margin. Only used when x is a cpr_cn object. Expected input is a list of length length(attr(x, "bspline_list")). Entries for elements marginal are ignored. If omitted, the midpoint between the boundary knots for each marginal is used.

n

the length of sequence to use for interpolating the spline function.

Value

a list with two elements

cn

the control net

surface

a data.frame with three columns to define the surface

See also

get_spline

Examples

# \donttest{
## Extract the control net and surface from a cpr_cn object.
a_cn <- cn(log10(pdg) ~ btensor(list(day, age, ttm)
           , df = list(15, 3, 5)
           , bknots = list(c(-1, 1), c(45, 53), c(-9, -1))
           , order = list(3, 2, 3))
           , data = spdg)

cn_and_surface <- get_surface(a_cn, n = 50)
str(cn_and_surface, max.level = 2)
#> List of 2
#>  $ cn     :'data.frame':	45 obs. of  3 variables:
#>   ..$ Var1: num [1:45] -1 -0.94 -0.829 -0.726 -0.619 ...
#>   ..$ Var2: num [1:45] 45 45 45 45 45 45 45 45 45 45 ...
#>   ..$ z   : num [1:45] -0.0363 -0.0704 -0.1904 -0.3311 -0.3755 ...
#>  $ surface:'data.frame':	10000 obs. of  3 variables:
#>   ..$ Var1: num [1:10000] -1 -0.98 -0.96 -0.939 -0.919 ...
#>   ..$ Var2: num [1:10000] 45 45 45 45 45 45 45 45 45 45 ...
#>   ..$ z   : num [1:10000] -0.0363 -0.0455 -0.0571 -0.0712 -0.0878 ...

old_par <- par()
par(mfrow = c(1, 2))
with(cn_and_surface$cn,
     plot3D::persp3D(unique(Var1),
                     unique(Var2),
                     matrix(z,
                            nrow = length(unique(Var1)),
                            ncol = length(unique(Var2))),
                     main = "Control Net")
     )
#> Warning: no DISPLAY variable so Tk is not available
with(cn_and_surface$surface,
     plot3D::persp3D(unique(Var1),
                     unique(Var2),
                     matrix(z,
                            nrow = length(unique(Var1)),
                            ncol = length(unique(Var2))),
                     main = "Surface")
     )


par(old_par)
#> Warning: graphical parameter "cin" cannot be set
#> Warning: graphical parameter "cra" cannot be set
#> Warning: graphical parameter "csi" cannot be set
#> Warning: graphical parameter "cxy" cannot be set
#> Warning: graphical parameter "din" cannot be set
#> Warning: graphical parameter "page" cannot be set
# }