如何选择块的第一行来定义条件并重新构造每个块中的后续行？

Question

我有一个数据框，看起来像这样：

trialcode response block
AM2A3     0        1
Empathy   1        1
ToM       4        1
Transfer  2.5      1
AM2D1     0        2
Empathy   4        2
ToM       2        2
Transfer  6        2
AM4M1     0        3
Empathy   6        3
ToM       6        3
Transfer  10       3

在每个块中，第一行定义试验条件，后面三行是我的因变量。我想把它重新组织成这样：

Empathy ToM Transfer condition block
1       4   2.5      AM2A3     1
4       2   6        AM2D1     2
6       6   10       AM4M1     3

有人能帮上忙吗？谢谢！

Answer 1

可选解决方案：

library(data.table)
dt[,.(Empathy = .SD[trialcode == "Empathy", response],
      Tom = .SD[trialcode == "ToM", response], 
      Transfer = .SD[trialcode == "Transfer", response],
      condition = head(trialcode,1)),
    by = block]

数据：

dt <- fread("
trialcode response block
AM2A3     0        1
Empathy   1        1
ToM       4        1
Transfer  2.5      1
AM2D1     0        2
Empathy   4        2
ToM       2        2
Transfer  6        2
AM4M1     0        3
Empathy   6        3
ToM       6        3
Transfer  10       3
")

Answer 2

库(data.table)

DT <- setDT(mydata)
# wrangling before casting
DT[, condition := trialcode[1], by = .(block)]
# cast 2nd - nth row of each group
dcast(DT[, .SD[2:.N], by = .(condition)], 
      block + condition ~ trialcode, value.var = "response")
#    block condition Empathy ToM Transfer
# 1:     1     AM2A3       1   4      2.5
# 2:     2     AM2D1       4   2      6.0
# 3:     3     AM4M1       6   6     10.0

Answer 3

欢迎加入SO！这应该是可行的：

library(tidyverse)
    output <- data %>% 
  mutate(response = ifelse(response == 0, trialcode, response)) %>% 
  mutate(trialcode = ifelse(str_starts(trialcode,"AM"), "condition", trialcode)) %>% 
  pivot_wider(names_from = trialcode, values_from = response) %>% 
  relocate(Empathy, ToM, Transfer, condition, block)

使用的数据：

data <- data.frame(trialcode = c("AM2A3","Empathy","ToM","Transfer","AM2D1","Empathy","ToM","Transfer"),
                 response = c(0,1,4,2.5,0,4,2,6),
                 block = c(1,1,1,1,2,2,2,2))

输出：

Empathy ToM   Transfer condition block
  <chr>   <chr> <chr>    <chr>     <dbl>
1 1       4     2.5      AM2A3         1
2 4       2     6        AM2D1         2