r语言 - 如何通过基于行值创建新变量来重塑数据框架以进行分析

Question

是否有一种方法可以从olddf中获得newdf，通过为列名创建一个新变量和为结果创建一个变量?谢谢你。

olddf <- data.frame('A' = c('Z1','Z2','Z3'), 
'B' = c(100, 200, 500),
'C' = c(90, 50, 60),
'D' = c(NA, 50, NA))
newdf <- data.frame('A' = c('Z1','Z2','Z3','Z1','Z2','Z3'), 
'B' = c(100, 200, 500, 100, 200, 500),
'var' = c('C', 'C', 'C', 'D', 'D', 'D'),
'res' = c(90, 50, 60, NA, 50, NA))

Answer 1

library(reshape2)
melt(olddf, id.vars = c('A','B'), value.name = 'res')

Answer 2

您也可以从tidyr中获取pivot_longer:

library(tidyverse)
pivot_longer(olddf, cols = c(C,D), names_to = "var", values_to = "res") %>%
arrange(var)

结果:

# A tibble: 6 x 4
A         B var     res
<chr> <dbl> <chr> <dbl>
1 Z1      100 C        90
2 Z2      200 C        50
3 Z3      500 C        60
4 Z1      100 D        NA
5 Z2      200 D        50
6 Z3      500 D        NA