重塑 - 防止分类变量在列上重复

Question

我想把 table 从长改成宽。它有多个值和一个分类变量。

table 看起来像：

df <- data.frame(name = c("john", "mary", "john", "mary"), 
variable = c("math", "math", "science", "science"), 
grade = c("sixth", "sixth", "sixth", "sixth"), 
val1 = c(78, 88, 97, 100), val2 = c(92, 83, 69, 94))

我想要的是：

want <- data.frame(name = c("john", "mary"), grade = c("sixth", "sixth"),
math.val1 = c(78, 88), math.val2 = c(92, 83), science.val1 = c(97, 100), 
science.val2 = c(69, 94))

没有成绩栏，我可以轻松实现：

reshape(df, idvar='name', timevar='variable', direction='wide')

在 "grade" 列中，我得到：

  name grade.math val1.math val2.math grade.science val1.science val2.science
1 john      sixth        78        92         sixth           97           69
2 mary      sixth        88        83         sixth          100           94

我该如何纠正这个问题？

谢谢。

Answer 1

您需要将 'grade' 包含到 idvar 中。

reshape(df, idvar=c('name', 'grade'), timevar='variable', direction='wide')

Answer 2

使用 data.table 的 devel 版本，即 v1.9.5，可以使用 dcast 重塑多个值列。它可以从 here

安装

library(data.table)
dcast(setDT(df), name+grade~variable, value.var=c('val1', 'val2'))
#   name grade math_val1 science_val1 math_val2 science_val2
#1: john sixth        78           97        92           69
#2: mary sixth        88          100        83           94

重塑 - 防止分类变量在列上重复

reshape - prevent categorical variable from repeating over columns

r

reshape