对此data.table R代码是否有一种整洁/最简单的方法？

Question

来自OECD数据的STRATUM太长了，为简单起见，我使用了这个名称，并希望将其简化为更简短，更精确的命名，如下面的代码所示。

pisaMas[,`:=`
             (SchoolType = c(ifelse(STRATUM == "National Secondary School", "Public", 
                                    ifelse(STRATUM == "Religious School", "Religious", 
                                           ifelse(STRATUM == "MOE Technical School", "Technical",0)))))]
pisaMas[,table(SchoolType)]

我想知道是否有一种简单的方法可以使用data.table包来解决此问题。

Answer 1

在这种情况下，data.table的当前开发版本具有新功能fcase（根据SQL CASE WHEN建模）：

pisaMas[ , SchoolType := fcase(
  STRATUM == "National Secondary School", "Public", 
  STRATUM == "Religious School", "Religious", 
  STRATUM == "MOE Technical School", "Technical",
  default = ''
)]
pisaMas[ , table(SchoolType)]

要获得开发版本，请尝试

install.packages(
  'data.table', type = 'source',repos = 'http://Rdatatable.github.io/data.table'
)

如果简单安装不起作用，您可以查看安装Wiki以获得更多详细信息：

https://github.com/Rdatatable/data.table/wiki/Installation

您也可以通过查找表解决此问题，有关详细信息，请参见此问答：

https://stackoverflow.com/a/36391018/3576984

Answer 2

这是我经过一番思考后得出的结果。

#' First I create a function (rname.SchType) that have oldname and newname using else if:

rname.SchType <- function(x){
  if (is.na(x)) NA
  else if (x == "MYS - stratum 01: MOE National Secondary School\\Other States")"Public"
  else if(x == "MYS - stratum 02: MOE Religious School\\Other States")"Religious" 
  else if(x == "MYS - stratum 03: MOE Technical School\\Other States")"Technical"
  else if(x == "MYS - stratum 04: MOE Fully Residential School")"SBP"
  else if(x == "MYS - stratum 05: non-MOE MARA Junior Science College\\Other States")"MARA"
  else if(x == "MYS - stratum 06: non-MOE Other Schools\\Other States")"Private"
  else if(x == "MYS - stratum 07: Perlis non-“MOE Fully Residential Schools”")"Perlis Fully Residential"
  else if(x == "MYS - stratum 08: Wilayah Persekutuan Putrajaya non-“MOE Fully Residential Schools”")"Putrajaya Fully Residential"
  else if(x == "MYS - stratum 09: Wilayah Persekutuan Labuan non-“MOE Fully Residential Schools”")"Labuan Fully Residential"
}

通过使用我刚创建的函数，通过在data.table中应用基数R（应用），将它通过一行代码粘贴到了data.table中，从而避免了代码混乱并且看起来更加简单：

pisaMalaysia[,`:=`(jenisSekolah = sapply(STRATUM,rname.SchType))]