Concatenate multiple columns into one with dplyr

问题

I have a df structured like this, but with a large number of columns and rows:

 A   B   C   D 
 1   4   3   3

and I want to obtain a df with a single column, made by the concatenation of all the previous elements:

 A
 1
 B
 4
 C
 3
 D
 3

How can I do? Better if solutions comprise the use of dplyr.

回答1:

unlist and wrap it in data.frame

data.frame(col = unlist(df), row.names = NULL)

#  col
#1   A
#2   1
#3   B
#4   4
#5   C
#6   3
#7   D
#8   3

---

Or making it as tibble

library(tibble)
tibble(col = unlist(df))

#   col  
#  <fct>
#1   A    
#2   1    
#3   B    
#4   4    
#5   C    
#6   3    
#7   D    
#8   3    

---

Another option mentioned by @Sotos is stack but it needs columns of class characters

df[] <- lapply(df, as.character)
stack(df)[1]

data

df <- read.table(text = "A   B   C   D 
                         1   4   3   3")

回答2:

In tidyverse, use gather

library(tidyverse)
gather(df) %>% 
     select(value)

来源：https://stackoverflow.com/questions/55025372/concatenate-multiple-columns-into-one-with-dplyr