我非常担心这个问题已经被问过并且会被踩,但我在文档中没有找到答案(?"["), 而且发现很难搜索。
data(wines)
# This is allowed:
alcoholic <- wines[, 1]
alcoholic <- wines[, "alcohol"]
nonalcoholic <- wines[, -1]
# But this is not:
fail <- wines[, -"alcohol"]
我知道有两种解决方案,但因需要它们而感到沮丧。
win <- wines[, !colnames(wines) %in% "alcohol"] # snappy
win <- wines[, -which(colnames(wines) %in% "alcohol")] # snappier!
setdiff
。你认为-“alcohol”
会返回什么?它本身不起作用,那么在尝试进行子集操作时为什么会起作用呢? - A5C1D2H2I1M1N2O1R2T1?[
来看:“对于[
-索引:i、j等可以是逻辑向量(你的!
替代方案)[...]也可以是负整数(你的which
替代方案)。 - Henrikwines[names(wines)!="alcohol"]
- plannapus