用lapply计算三列的平均值一直报错,计算其中俩列无错,请问为何?代码如下:
rt = data.frame(q1 = rep(1,10),
q2 = seq(1,10),
q3 = runif(10,1,10))
rt
colnames(rt) = c("q1","q2","q3")
rt$mean = lapply(rt[, c("q1","q2","q3")],mean)
rt$mean = lapply(rt[, c("q1","q2")],mean)
rt$mean = lapply(rt[, c("q1","q3")],mean)
rt$mean = lapply(rt[, c("q2","q3")],mean)