问题描述
我有一个数据集，其中观察结果以行给出，但是我想创建一个面板，其中观察值以列给出。例如：
A<-as.data.frame(rbind(c('A','B','C',5,6),c('A','D',2,3)))
colnames(A)<-c('State','County','City',1983,1984)
> A
State County City 1983 1984
1 A B C 5 6
2 A B D 2 3
如果我运行以下代码：
library(dplyr)
B<-B%>%
group_by(State,County,City)%>%
do(data.frame(year=seq(1983,1984,by=1)))
B<-cbind(B,0)
colnames(B)[5]<-'val'
for(i in unique(B$State)){
for(j in unique(B$County)){
for(k in unique(B$City)){
B$val[B$State==i&B$County==j&B$City==k]<-as.matrix(A[A$State==i&A$County==j&A$City==k,4:5])
}
}
}
B<-as.data.frame(B)
然后我得到
> B
State County City year val
1 A B C 1983 5
2 A B C 1984 6
3 A B D 1983 2
4 A B D 1984 3
我希望能够做到这一点，但最后不要求助于for循环，因为for循环在处理具有大量观察值的数据集时实际上效率很低（我的实际数据集有100,000个观察值）。
解决方法
使用tidyr的ivot_longer：
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