Question

我有一个数据帧数据。我想为每行选择带符号的最大绝对值。

 set.seed(10987) 
dat = data.frame( V1 = letters[1:5], V2 = rnorm(5), V3 = rnorm(5), V4 =(rnorm(5)))

预期产出

 dat
      V1         V2         V3         V4        max
      a -0.6357365 -0.3928079 -0.5059575 -0.6357365
      b -0.4616447 -0.3199929  1.3430388  1.3430388
      c  1.4322822 -0.2791133 -0.2145794  1.4322822
      d -0.6506964  0.4941883 -0.1795565 -0.6506964
      e -0.2073807 -0.1773305 -0.1001907 -0.2073807

Answer 1

我们可以使用row/column索引。我们得到每行中绝对最大元素的列索引，其中max.col，cbind包含行序列，根据索引提取值，并创建一个新列max < / p>

dat$max <- dat[-1][cbind(1:nrow(dat), max.col(abs(dat[-1])))]
dat$max
#[1] -0.6357365  1.3430388  1.4322822 -0.6506964 -0.2073807

数据

dat <- structure(list(V1 = c("a", "b", "c", "d", "e"), V2 = c(-0.6357365, 
-0.4616447, 1.4322822, -0.6506964, -0.2073807), V3 = c(-0.3928079, 
-0.3199929, -0.2791133, 0.4941883, -0.1773305), V4 = c(-0.5059575, 
1.3430388, -0.2145794, -0.1795565, -0.1001907)), .Names = c("V1", 
"V2", "V3", "V4"), row.names = c(NA, -5L), class = "data.frame")

如何返回R中每行的带符号最大绝对值

1 个答案:

数据