试了一个语句，但是一直跳错，求高手帮忙指正一下

> data_split <- function(season,mxPH){
    c <- file(season,"r")
    varnames <- paste("splitfile",1:10,sep="_")
    i <- 1
    while(TRUE){
    assign(varnames[i],value = readLines(c, n= mxPH))
    write.table(get(varnames[i],paste(varnames[i],".txt",sep =""))
    if(length(varnames[i]))< ncol) break
    else i <- i+1
}
    return(i)
}

找到了方法和大家共勉吧
set.seed(1234568)
X.samp <- sample(n,round(n*0.8))
XTrn <- X[X.samp,]
XTst <- X[-X.samp,]

举一反三再分享一个方式：
> nX <- dim(X)[1]
> ntr <- round(nX*0.8)
> a1 <- X[sample(1:nX),]
> Xtr <- X[(1:ntr),]
> Xts <- X[(ntr+1):n,]