R dplyr：创建面板数据的理货

Question

我有以下数据框：

D <- data.frame("Id" = c("a","b","c","d","e","f","g"), "Group" = c("1","1","1","2","2","2","2"),"Time" = c("1","1","2","1","2","3","3"))

  Id Group Time
1  a     1    1
2  b     1    1
3  c     1    2
4  d     2    1
5  e     2    2
6  f     2    3
7  g     2    3

我想按周期和时间统计个体的数量，保持圆柱结构。经典的方法是使用 dplyr

D %>% group_by(Group,Time) %>% tally()
  Group Time      n
  <fct> <fct> <int>
1 1     1         2
2 1     2         1
3 2     1         1
4 2     2         1
5 2     3         2

但结构不平衡：时间 3 没有出现在第 1 组中，但我希望看到它与 0 相关联，如下所示：

  Group Time      n
  <fct> <fct> <int>
1 1     1         2
2 1     2         1
3 1     3         0
4 2     1         1
5 2     2         1
6 2     3         2

有没有办法平衡 group_by 后的结果？有人遇到过类似的事情吗？提前致谢

Answer 1

由于 Time 是因子变量，我们可以将 count 与 .drop = FALSE 一起使用，因为默认情况下 count 会丢弃计数为 0 的观察值。

library(dplyr)
D %>% count(Group, Time, .drop = FALSE)

#  Group Time      n
#  <fct> <fct> <int>
#1 1     1         2
#2 1     2         1
#3 1     3         0
#4 2     1         1
#5 2     2         1
#6 2     3         2

我们也可以使用相同的方法使用 tally。

D %>% group_by(Group,Time, .drop = FALSE) %>% tally()

或 complete

D %>%  count(Group, Time) %>% tidyr::complete(Group, Time, fill = list(n = 0))

Answer 2

Ronak Shah 回答的小替代方案：

library(tidyr)
library(dplyr)

D <- data.frame("Id" = c("a","b","c","d","e","f","g"), "Group" = c("1","1","1","2","2","2","2"),"Time" = c("1","1","2","1","2","3","3"))

D %>% 
  group_by(Group,Time) %>% 
  tally() %>% 
  ungroup() %>%
  complete(Group, Time)

Answer 3

在base R中，我们可以使用table

as.data.frame(table(D[-1]))

R dplyr：创建面板数据的理货

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