R reshape2 dcast：转换数据

Question

如何将数据 X 转换为 Y，如

X = data.frame(
  ID = c(1,1,1,2,2),
  NAME = c("MIKE","MIKE","MIKE","LUCY","LUCY"),
  SEX = c("MALE","MALE","MALE","FEMALE","FEMALE"),
  TEST = c(1,2,3,1,2),
  SCORE = c(70,80,90,65,75)
)

Y = data.frame(
  ID = c(1,2),
  NAME = c("MIKE","LUCY"),
  SEX = c("MALE","FEMALE"),
  TEST_1 =c(70,65),
  TEST_2 =c(80,75),
  TEST_3 =c(90,NA)
)

reshape2 中的 dcast 函数似乎可以工作，但它不能在数据中包含其他列，如上例中的 ID、NAME 和 SEX。

假设ID列的所有其他列都一致，比如Mike只能是ID为1的男性，怎么办？

Answer 1

根据文档 (?reshape2::dcast)，dcast() 允许公式中的 ...：

"..." represents all other variables not used in the formula ...

reshape2 和 data.table 软件包均支持 dcast()。

所以，你可以这样写：

reshape2::dcast(X, ... ~ TEST, value.var = "SCORE")
#  ID NAME    SEX  1  2  3
#1  1 MIKE   MALE 70 80 90
#2  2 LUCY FEMALE 65 75 NA

但是，如果OP坚持列名应该是TEST_1、TEST_2等，则TEST列需要在整形前修改。这里使用了data.table：

library(data.table)
dcast(setDT(X)[, TEST := paste0("TEST_", TEST)], ... ~ TEST, value.var = "SCORE")
#   ID NAME    SEX TEST_1 TEST_2 TEST_3
#1:  1 MIKE   MALE     70     80     90
#2:  2 LUCY FEMALE     65     75     NA

这与 data.frame Y.

给出的预期答案一致

R reshape2 dcast：转换数据

R reshape2 dcast: transform data

r

reshape2

dcast