相关疑难解决方法(0)

提前感谢您阅读本文.我有一个在data.table 1.9.3上工作正常的函数.但今天我更新了我的data.table包,我的功能不起作用.

这是我在data.table 1.9.3上的函数和工作示例:

trait.by <- function(data,traits="",cross.by){
  traits = intersect(traits,names(data))
  if(length(traits)<1){  
    #if there is no intersect between names and traits
    return(      data[,       list(N. = .N),    by=cross.by])
  }else{
    return(data[,c(   N. = .N,
                    MEAN = lapply(.SD,function(x){return(round(mean(x,na.rm=T),digits=1))}) , 
                    SD   = lapply(.SD,function(x){return(round(sd  (x,na.rm=T),digits=2))}) ,
                    'NA' = lapply(.SD,function(x){return(sum  (is.na(x)))})),
                 by=cross.by, .SDcols = traits])
  }
}

> trait.by(data.table(iris),traits = c("Sepal.Length",    "Sepal.Width"),cross.by="Species")
#      Species N. MEAN.Sepal.Length MEAN.Sepal.Width SD.Sepal.Length
#1:     setosa 50               5.0              3.4            0.35
#2: versicolor 50               5.9              2.8            0.52
#3:  virginica 50               6.6              3.0            0.64
# …