r - 根据存在的数据帧行分配分组变量R

Question

我在 R 中有一个这样的列表:

cat1  
cat7  
cat10  
cat4  
frog  
dino11  
dino12  
dino15  
rabbit  

我需要制作一个如下所示的新数据框:

cat1 frog  
cat7 frog  
cat10 frog  
cat4 frog  
dino11 rabbit  
dino12 rabbit  
dino15 rabbit

想法？谢谢!

Answer 1

我们根据'v1'中数字的非出现创建一个分组变量，取lag，创建一个新列'v2'作为last 'v1' 的元素，删除每个组的last 行并选择 感兴趣的列

library(tidyverse)
df %>%
  group_by(grp = lag(cumsum(grepl("^[^0-9]+$", v1)), default = 0)) %>% 
  mutate(v2 = last(v1)) %>% 
  slice(-n()) %>%
  ungroup %>%
  select(-grp)
# A tibble: 7 x 2
#  v1     v2    
#  <chr>  <chr> 
#1 cat1   frog  
#2 cat7   frog  
#3 cat10  frog  
#4 cat4   frog  
#5 dino11 rabbit
#6 dino12 rabbit
#7 dino15 rabbit

数据

df <- structure(list(v1 = c("cat1", "cat7", "cat10", "cat4", "frog", 
"dino11", "dino12", "dino15", "rabbit")), .Names = "v1",
 class = "data.frame", row.names = c(NA, -9L))