Question

我正在尝试将风向（值0-360）转换为基本方向（即NW）。我的代码如下：

DegToDer <- function(degree) {
  value <- as.integer((degree / 45)+ .5)
  direction <- c("N","NE","E","SE","S","SW","W","NW")
  return(direction[((value+1) %% 8)])}

在列上运行它时，出现以下错误：

替换有346行，数据有365

我已经用几个值对其进行了测试，发现应该返回值“ NE”的所有东西都只返回“ character（0）”

> DegToDer(293)
character(0)
> DegToDer(292)
[1] "W"
> DegToDer(360)
[1] "N"

在此问题上的任何协助都将不胜感激！

Answer 1

因此，这里的问题是R索引向量从1开始，因此如果您提供的值像floor((293/45)+0.5)+1一样返回8，则索引将是0，函数返回值将是NA

您如何尝试使用基本的R函数cut？

DegToDer <- function (degree) {
  return(cut(
    x = degree,
    breaks = c(0, seq(22.5, 337.5, 45), 360),
    labels = c("N","NE","E","SE","S","SW","W","NW","N"),
    include.lowest = TRUE
  ))
}

Answer 2

您的%%公式有误。

degree <- 0:90

DegToDer <- function(degree) {
    value <- as.integer(degree / 45 + 0.5)
    direction <- c("N","NE","E","SE","S","SW","W","NW")
    return(direction[(value %% 8) + 1])
}

table(DegToDer(degree))
#> 
#>  E  N NE 
#> 23 23 45

^{由reprex package（v0.3.0）于2019-11-04创建}

R函数返回“字符（0）”而不是基本方向

2 个答案: