R将行添加到每组中，使每组具有相同的编号，并指定其他变量

Question

这是我的df:

df = tibble(week = c(1,1,2,2,3,3,3,4,4,4,4),
session = c(1,2,1,2,1,2,3,1,2,3,4),
work =rep("done",11))
df
# A tibble: 11 x 3
week session work 
<dbl>   <dbl> <chr>
1     1       1 done 
2     1       2 done 
3     2       1 done 
4     2       2 done 
5     3       1 done 
6     3       2 done 
7     3       3 done 
8     4       1 done 
9     4       2 done 
10     4       3 done 
11     4       4 done 

对于每个week，应该有4行，会话1到4。如何添加"；缺少"；会话行(其余变量为NA(，因此df为：

df1= tibble(week =  c(rep(1,4), rep(2,4), rep(3,4), rep(4,4)),
session = rep(1:4,4),
work = c("done", "done" ,NA, NA, "done", "done" ,NA, NA,"done", "done" ,"done", NA, rep("done",4)))
df1
week session work 
<dbl>   <int> <chr>
1     1       1 done 
2     1       2 done 
3     1       3 NA   
4     1       4 NA   
5     2       1 done 
6     2       2 done 
7     2       3 NA   
8     2       4 NA   
9     3       1 done 
10     3       2 done 
11     3       3 done 
12     3       4 NA   
13     4       1 done 
14     4       2 done 
15     4       3 done 
16     4       4 done 

Answer 1

tidyr::complete(df, week, session)
# A tibble: 16 x 3
week session work 
<dbl>   <dbl> <chr>
1     1       1 done 
2     1       2 done 
3     1       3 NA   
4     1       4 NA   
5     2       1 done 
6     2       2 done 
7     2       3 NA   
8     2       4 NA   
9     3       1 done 
10     3       2 done 
11     3       3 done 
12     3       4 NA   
13     4       1 done 
14     4       2 done 
15     4       3 done 
16     4       4 done 

Answer 2

如果的速度很重要，这里有一个data.table解决方案

# load package
library(data.table)
# set as data table
setDT(df)
# cross join to get complete combination
week <- 1:4
session <- 1:4
z <- CJ(week,session)
# join
df_1 <- df[z, on=.(week, session)]