r-组合不同长度的长格式数据帧并转换为宽格式

Question

由于time变量(不平衡面板数据(，我想组合不同长度的长格式数据帧：

set.seed(63)
#function to create a data frame that includes id, time and x
func1 <- function (size=5) {
x=sample(c(0,1), 1)
data.frame(time=1:size, x=x)}

#function to row combine data frames
func2 <- do.call("rbind", Map(function(x,y) {
data.frame(id=x, func1(y))
}, 1:5, 5))

#Sample 10 observations to create imbalanced panel data
dd <- func2[sample(nrow(func2), 10), ]  
fd <- dd[with(dd, order(id, time)),]
> fd
id time x
1   1    1 0
2   1    2 0
3   1    3 0
4   1    4 0
5   1    5 0
10  2    5 1
13  3    3 0
17  4    2 0
18  4    3 0
21  5    1 0

最后，我想将其转换为宽格式，并使用NA填充基于time变量的x的跳过单元格。类似这样的东西：

id    x.time1 x.time2 x.time3 x.time4 x.time5 
1       0       0       0       0       0
2       NA      NA      NA      NA      1
3       NA      NA      0       NA      NA
4       NA      0       0       NA      NA
5       0       NA      NA      NA      NA

Answer 1

使用data.table

library(data.table)
dcast(setDT(fd), id ~ paste0('x.time', time), value.var = 'x')

-输出

id x.time1 x.time2 x.time3 x.time4 x.time5
1:  1       0       0       0       0       0
2:  2      NA      NA      NA      NA       1
3:  3      NA      NA       0      NA      NA
4:  4      NA       0       0      NA      NA
5:  5       0      NA      NA      NA      NA

Answer 2

一个可能的解决方案：

library(tidyverse)
fd <- data.frame(
id = c(1L, 1L, 1L, 1L, 1L, 2L, 3L, 4L, 4L, 5L),
time = c(1L, 2L, 3L, 4L, 5L, 5L, 3L, 2L, 3L, 1L),
x = c(0L, 0L, 0L, 0L, 0L, 1L, 0L, 0L, 0L, 0L)
)
fd %>% 
pivot_wider(id, names_from = time, values_from = x, names_prefix = "x.time")
#> # A tibble: 5 × 6
#>      id x.time1 x.time2 x.time3 x.time4 x.time5
#>   <int>   <int>   <int>   <int>   <int>   <int>
#> 1     1       0       0       0       0       0
#> 2     2      NA      NA      NA      NA       1
#> 3     3      NA      NA       0      NA      NA
#> 4     4      NA       0       0      NA      NA
#> 5     5       0      NA      NA      NA      NA