正在寻找ApproxFun的2D版本() [英] Seeking 2D version of approxfun()

问题描述

我正在R中寻找stats::approxfun()的2D版本，它可以从(x，y，z)数据集生成内插函数f(x，y)。我在包akima或其他地方找不到。

推荐答案

我会尝试重新调整R包fields中的interp.surface函数。改编自?interp.surface的示例：

加载包

library(fields)
#> Warning: package 'fields' was built under R version 4.1.2
#> Loading required package: spam
#> Warning: package 'spam' was built under R version 4.1.2
#> Loading required package: dotCall64
#> Warning: package 'dotCall64' was built under R version 4.1.2
#> Loading required package: grid
#> Spam version 2.7-0 (2021-06-25) is loaded.
#> Type 'help( Spam)' or 'demo( spam)' for a short introduction 
#> and overview of this package.
#> Help for individual functions is also obtained by adding the
#> suffix '.spam' to the function name, e.g. 'help( chol.spam)'.
#> 
#> Attaching package: 'spam'
#> The following objects are masked from 'package:base':
#> 
#>     backsolve, forwardsolve
#> Loading required package: viridis
#> Loading required package: viridisLite
#> 
#> Try help(fields) to get started.

加载数据

data(lennon)
obj <- list(x = 1:20, y = 1:20, z = lennon[201:220, 201:220])

定义近似函数

approxfun_2d <- function(x, y) {
  interp.surface(obj, cbind(x, y))
}

测试

set.seed(1)
approxfun_2d(x = runif(1, min = 1, max = 20), y = runif(1, min = 1, max = 20))
#> [1] 33.34148

绘制原始数据

image.plot(obj)

计算内插

x_interp <- runif(2e2, 1, 20)
y_interp <- runif(2e2, 1, 20)
z_interp <- approxfun_2d(x_interp, y_interp)

曲线图近似

quilt.plot(x_interp, y_interp, z_interp)

^{由reprex package(v2.0.1)}在2021-11-23创建

这不是100%等同于approxfun的2D版本，但对于大多数用途来说可能足够好。

这篇关于正在寻找ApproxFun的2D版本()的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！