以这个样本变量为例
df <- data.frame(month=rep(1:3,2),
student=rep(c("Amy", "Bob"), each=3),
A=c(9, 7, 6, 8, 6, 9),
B=c(6, 7, 8, 5, 6, 7))
我可以使用tidyr中的spread将其更改为宽格式.
> df[, -4] %>% spread(student, A)
month Amy Bob
1 1 9 8
2 2 7 6
3 3 6 9
但是，我如何将两个值(例如A和B)进行扩散，从而使输出类似于
month Amy.A Bob.A Amy.B Bob.B
1 1 9 8 6 5
2 2 7 6 7 6
3 3 6 9 8 7
这里有一个简单而高效的解决方案，使用data.table
library(data.table) ## v >= 1.9.6
dcast(setDT(df), month ~ student, value.var = c("A", "B"))
# month Amy_A Bob_A Amy_B Bob_B
# 1: 1 9 8 6 5
# 2: 2 7 6 7 6
# 3: 3 6 9 8 7
或者一个可能的解决方案
df %>%
gather(variable, value, -(month:student)) %>%
unite(temp, student, variable) %>%
spread(temp, value)
# month Amy_A Amy_B Bob_A Bob_B
# 1 1 9 6 8 5
# 2 2 7 7 6 6
# 3 3 6 8 9 7
EDIT 22/10/2019
正如@gjabel comments 中提到的，更新的tidyr版本(v1.0.0+)
pivot_wider(data = df,
id_cols = month,
names_from = student,
values_from = c("A", "B"))
# # A tibble: 3 x 5
# month A_Amy A_Bob B_Amy B_Bob
# <int> <dbl> <dbl> <dbl> <dbl>
# 1 1 9 8 6 5
# 2 2 7 6 7 6
# 3 3 6 9 8 7