如何为每一行中的每对观察创建一个新列 - R Language

Question

I would like to change my tibble so that every observation gets paired with the following observation into a new row, while retaining the id.

x1 <- c("cook", "clean", "wash", "walk", "wish", "broom", "clean", "wash", "walk", "cook")
x2 <- c("move", "climb", "skate", "ball", "climb", "jog", "job", "skate", "ball", "climb")
x3 <- c("try", "clean", "boom", "walk", "bring", "broom", "sing", "wash", "jump", "fly")

df <- tibble(y, x1, x2, x3)```


In this situation, 

```row 1 should be: y=1, x1="cook", x2="move"
row 2 should be: y=1, x2="move", x3="try"
row 3 should be: y=2, x1="clean",  x2="climb"
row 4 should be: y=2, x2="climb", x3="clean"```

I might have to iterate the process where the number of observations "x" is roughly equal to 50.

Thank you so much for the help!

Answer 1

Improved Answer

Re-reading your question, I realize you need it to work for x1, x2 ... x50 , so I've rewritten the answer to be more flexible. Just include x1:x50 in the pivot_longer call instead of x1:x3 .

df %>% 
  pivot_longer(names_to="obs", values_to="val", x1:x3) %>% 
  group_by(y) %>% 
  mutate(x1 = val, x2 = lead(val)) %>% 
  filter(!is.na(x2)) %>% 
  select(y, x1, x2)

Output:

# A tibble: 20 x 3
# Groups:   y [10]
       y x1    x2   
   <int> <chr> <chr>
 1     1 cook  move 
 2     1 move  try  
 3     2 clean climb
 4     2 climb clean
 5     3 wash  skate
 6     3 skate boom 
 7     4 walk  ball 
 8     4 ball  walk 
 9     5 wish  climb
10     5 climb bring
11     6 broom jog  
12     6 jog   broom
13     7 clean job  
14     7 job   sing 
15     8 wash  skate
16     8 skate wash 
17     9 walk  ball 
18     9 ball  jump 
19    10 cook  climb
20    10 climb fly  

Initial Answer

Is this the pattern you need?

df %>%
  bind_rows(df) %>%
  arrange(y) %>%
  group_by(y) %>%
  mutate(x1_new = if_else(row_number() == 1, x1, x2),
         x2_new = if_else(row_number() == 1, x2, x3)) %>%
  select(y, x1_new, x2_new)

Output:

# A tibble: 20 x 3
# Groups:   y [10]
       y x1_new x2_new
   <int> <chr>  <chr> 
 1     1 cook   move  
 2     1 move   try   
 3     2 clean  climb 
 4     2 climb  clean 
 5     3 wash   skate 
 6     3 skate  boom  
 7     4 walk   ball  
 8     4 ball   walk  
 9     5 wish   climb 
10     5 climb  bring 
11     6 broom  jog   
12     6 jog    broom 
13     7 clean  job   
14     7 job    sing  
15     8 wash   skate 
16     8 skate  wash  
17     9 walk   ball  
18     9 ball   jump  
19    10 cook   climb 
20    10 climb  fly