如何取消透视 R 数据框中的特定列

Question

我有一个 R 格式的数据框，如下面第一个 table 所示。我想将“M1.1”、“M1.2”和“M1.3”列合并到一个“M1”列中，以便条目位于它们自己的行中（其他列中的 id 和值将重复）如第二个table所示。我可以使用什么功能来完成此操作？

id	M1.1	M1.2	M1.3	M2	M3	M4	M5	M6
test a	test t	test a	test y	test	test t	test y	test u	test w
test s	test r	test a	test h	test r	test j	test j	test w	test d

id	M1	M2	M3	M4	M5	M6
test a	test t	test	test t	test y	test u	test w
test a	test a	test	test t	test y	test u	test w
test a	test y	test	test t	test y	test u	test w
test s	test r	test r	test j	test j	test w	test d
test s	test a	test r	test j	test j	test w	test d
test s	test h	test r	test j	test j	test w	test d

Answer 1

我们可以使用 pivot_longer:

library(dplyr)
library(tidyr)
df %>% 
    pivot_longer(
        cols = c(M1.1, M1.2, M1.3),
        names_to = "names",
        values_to = "M1"
    ) %>% 
    select(id, M1, M2:M6)

 A tibble: 6 x 7
  id     M1     M2     M3     M4     M5     M6    
  <chr>  <chr>  <chr>  <chr>  <chr>  <chr>  <chr> 
1 test a test t test   test t test y test u test w
2 test a test a test   test t test y test u test w
3 test a test y test   test t test y test u test w
4 test s test r test r test j test j test w test d
5 test s test a test r test j test j test w test d
6 test s test h test r test j test j test w test d

数据：

structure(list(id = c("test a", "test s"), M1.1 = c("test t", 
"test r"), M1.2 = c("test a", "test a"), M1.3 = c("test y", "test h"
), M2 = c("test", "test r"), M3 = c("test t", "test j"), M4 = c("test y", 
"test j"), M5 = c("test u", "test w"), M6 = c("test w", "test d"
)), row.names = c(NA, -2L), class = c("tbl_df", "tbl", "data.frame"
))

Answer 2

使用@TarJae 数据，大概更快data.table:

library(data.table)

dat <- data.table(dat)

melt(dat, , paste('M1', 1:3, sep = '.'), , 'M1')[
  order(id),
  c('id', paste('M', 1:6, sep = ''))
]

#        id     M1     M2     M3     M4     M5     M6
# 1: test a test t   test test t test y test u test w
# 2: test a test a   test test t test y test u test w
# 3: test a test y   test test t test y test u test w
# 4: test s test r test r test j test j test w test d
# 5: test s test a test r test j test j test w test d
# 6: test s test h test r test j test j test w test d

如何取消透视 R 数据框中的特定列

How to unpivot specific columns in R dataframe

r

reshape

unpivot

data-wrangling