base 版：
tbl <- structure(list(t = c(1, 2, 3, 4, 5, 6), ak_b = c(909.021709977295,
957.828244741177, 1037.13886373248, 1122.55029956928, 1275.07072070641,
1415.38950815257), djk_b = c(2824.00501596013, 2975.62944634725,
3222.01914572632, 3487.36189890379, 3961.18824386354, 4397.10848122651
), ak_a = c(909.021709977295, 957.828244741177, 1037.13886373248,
1122.55029956928, 1275.07072070641, 1415.38950815257), djk_a = c(2824.00501596013,
2975.62944634725, 3222.01914572632, 3487.36189890379, 3961.18824386354,
4397.10848122651)), row.names = c(NA, -6L), class = "data.frame")
. <- tbl
. <- reshape(., direction = "long", idvar = 1, varying = list(2:5), v.names = "value", times = colnames(.)[-1])
.[, c("class1", "class2")] <- read.table(text = .$time, sep = "_")
within(., rm(time))
#> t value class1 class2
#> 1.ak_b 1 909.0217 ak b
#> 2.ak_b 2 957.8282 ak b
#> 3.ak_b 3 1037.1389 ak b
#> 4.ak_b 4 1122.5503 ak b
#> 5.ak_b 5 1275.0707 ak b
#> 6.ak_b 6 1415.3895 ak b
#> 1.djk_b 1 2824.0050 djk b
#> 2.djk_b 2 2975.6294 djk b
#> 3.djk_b 3 3222.0191 djk b
#> 4.djk_b 4 3487.3619 djk b
#> 5.djk_b 5 3961.1882 djk b
#> 6.djk_b 6 4397.1085 djk b
#> 1.ak_a 1 909.0217 ak a
#> 2.ak_a 2 957.8282 ak a
#> 3.ak_a 3 1037.1389 ak a
#> 4.ak_a 4 1122.5503 ak a
#> 5.ak_a 5 1275.0707 ak a
#> 6.ak_a 6 1415.3895 ak a
#> 1.djk_a 1 2824.0050 djk a
#> 2.djk_a 2 2975.6294 djk a
#> 3.djk_a 3 3222.0191 djk a
#> 4.djk_a 4 3487.3619 djk a
#> 5.djk_a 5 3961.1882 djk a
#> 6.djk_a 6 4397.1085 djk a
<sup>Created on 2021-06-01 by the reprex package (v2.0.0)</sup>
