我有以下data.frame：
> mydata <- data.frame(gene=rep(paste(sample(LETTERS, 10, replace=TRUE), sample(1:1000, 10, replace=FALSE), sep=''), each=5),
+ clus=rep(sample(c('clus1','clus2'),10,replace=TRUE), each=5),
+ treat=rep(LETTERS[1:5],10),
+ value=rnorm(n=50))
> head(mydata,10)
gene clus treat value
1 R22 clus2 A -0.25592597
2 R22 clus2 B 0.02956595
3 R22 clus2 C 0.36785764
4 R22 clus2 D -1.47393076
5 R22 clus2 E -2.09895513
6 S671 clus2 A -0.17079390
7 S671 clus2 B 1.73643010
8 S671 clus2 C 0.73169650
9 S671 clus2 D -0.85247328
10 S671 clus2 E 1.43589407
我有一个通用功能，其中第一步是像这样dcast和data.frame：
> dcast(mydata, gene+clus~treat, value.var="value")
gene clus A B C D E
1 B957 clus1 -2.0567334 2.27900277 0.714784782 2.5123012 -0.91194409
2 I55 clus2 -1.3044907 -1.06102427 -0.380294765 -0.1194413 1.90913241
3 M937 clus1 -2.1610684 1.82269937 0.716722593 -0.1525909 0.92291856
4 N986 clus1 0.2483086 -0.41405923 -0.714040214 -0.4243231 0.13645697
5 R22 clus2 -0.2559260 0.02956595 0.367857644 -1.4739308 -2.09895513
6 R295 clus2 -0.4673256 0.08302997 -0.352803402 0.2983689 1.25420084
7 R545 clus1 2.5655384 -0.14798670 1.001409732 0.1971712 -0.11440350
8 S671 clus2 -0.1707939 1.73643010 0.731696498 -0.8524733 1.43589407
9 W131 clus1 0.9915700 0.05430845 0.008878675 -1.7140515 0.06019417
10 Z302 clus1 1.2854086 0.09809435 -2.533077634 -1.0244764 -0.57606345
虽然这在函数外部起作用，但似乎在内部不起作用...我有这个最小的函数：
myfun <- function(mydf, groupvar, groupvar2, measurevar, valuevar){
newdf <- dcast(mydf, get(measurevar)+get(groupvar2)~get(groupvar), value.var=valuevar)#cannot change sep from "_"
}
但是当我调用它时，出现以下错误：
> myfun(mydata, "treat", "clus", "gene", "value")
get（measurevar）中的错误：找不到对象“ measurevar”
为什么我的函数找不到我传递的变量measurevar？
但是，如果我在return之前dcast，它会毫无问题地返回它，并且dcast突然起作用：
> myfun <- function(mydf, groupvar, groupvar2, measurevar, valuevar){
+ return(list(groupvar,groupvar2,measurevar,valuevar))
+ newdf <- dcast(mydf, get(measurevar)+get(groupvar2)~get(groupvar), value.var=valuevar)#cannot change sep from "_"
+ }
> myfun(mydata, "treat", "clus", "gene", "value")
[[1]]
[1] "treat"
[[2]]
[1] "clus"
[[3]]
[1] "gene"
[[4]]
[1] "value"
这是怎么回事？我真的什么都不懂……为什么dcast找不到我传递的变量measurevar，但是如果我先返回它，突然之间就会知道吗？
谢谢！