将多个电子表格组合到R中的一个数据框

Question

我以This link为参考

我原来的方法是：

DATA <- NULL
n <- length(list.files())

for (i in 1:n){
    wb <- loadWorkbook(list.files()[i])
    ws <- readWorksheet(wb, 
        sheet=getSheets(wb), header=TRUE, startRow=3, endCol=45)

    ws$Issue.Date <- as.Date(substr(ws$Issue.Date, 1, 10))   #i need to standardize the date format.
    ws$Flt.Date <- as.Date(substr(ws$Flt.Date, 1, 10))
    ws$Dnl.Date <- as.Date(substr(ws$Dnl.Date, 1, 10))
    ws$Ver.On <- as.Date(substr(ws$Ver.On, 1, 10))

    DATA <- rbind(DATA, ws)
}

虽然从链接中，它提到了do.call（rbind，...），所以我尝试了：

> DATA2 <- do.call(rbind, lapply(list.files(), function(x) {
+ wb <- loadWorkbook(x)
+ ws <- readWorksheet(wb,
+ sheet=getSheets(wb), header=TRUE, startRow=3, endCol=45)
+ ws$Issue.Date <- as.Date(substr(ws$Issue.Date, 1, 10))
+ ws$Flt.Date <- as.Date(substr(ws$Flt.Date, 1, 10))
+ ws$Dnl.Date <- as.Date(substr(ws$Dnl.Date, 1, 10))
+ ws$Ver.On <- as.Date(substr(ws$Ver.On, 1, 10))
+ }))
Warning message:
In (function (..., deparse.level = 1)  :
  number of columns of result is not a multiple of vector length (arg 1)

谢谢！