小编Big*_*LBL的帖子

在编程语言R中,恰恰是什么意思

'['

它在以下代码部分中充当sapply()和lapply()的参数:

dd <- data.frame(
    A = c(1L, 2L, 3L), 
    B = c(4L, 5L, 6L), 
    C = c("X1=7;X2=8;X3=9",
          "X1=13;X2=14",
          "X1=5;X2=1;X3=8")
)
namev <- function(x) {
    a <- strsplit(x,"=")
    setNames(sapply(a,'[',2), sapply(a,'[',1))
}

vv <- lapply(strsplit(as.character(dd$C),";"), namev)

nm <- unique(unlist(sapply(vv, names)))

#extract data from all rows for every column
nv <- do.call(rbind, lapply(vv, '[', nm))

dd $ C [1] X1 = 7; X2 = 8; X3 = 9 X1 ;; X1 = 13; X2 = 14
级:X1 ;; X1 = 13; …