带有变量的r drake文件输出名

我正在使用 drake 要创建多个输出文件,我要在其中通过变量指定路径。有点像

outpath <- "data"
outfile <- file.path(outpath, "mydata.csv")
write.csv(df, outfile)

但是 file_out 除了文字字符之外,似乎无法处理给它的参数。

给出一个小的代码示例:

代码设置

library(drake)

outpath <- "data"
# for reproducibility only
if (!dir.exists(outpath)) dir.create(outpath)

make_data <- function() data.frame(x = 1:10, y = rnorm(10))

工作代码

直接指定文件:

p0 <- drake_plan(
  df = make_data(),
  write.csv(df, file_out("data/mydata0.csv"))
)
make(p0)
#> target file "data/mydata0.csv"

失效代码

使用 file.path 建造出口

p1 <- drake_plan(
  df = make_data(),
  write.csv(df, file_out(file.path(outpath, "mydata1.csv")))
)
make(p1)
#> target file "mydata1.csv"
#> Error: The file does not exist: mydata1.csv
#> In addition: Warning message:
#> File "mydata1.csv" was built or processed,
#> but the file itself does not exist. 

我想德雷克只找到文本字符串作为目标,而不是 file.path(...) 例如,这也失败了

p2 <- drake_plan(
  df = make_data(),
  outfile = file.path(outpath, "mydata1.csv"),
  write.csv(df, file_out(outfile))
)
#> Error: found an empty file_out() in command: write.csv(df, file_out(outfile))

知道怎么解决吗?