add yaml header to R test file.

treat it properly in the code
update vignettes.
Fix #41

R/processData.R

@@ -274,16 +274,19 @@ DataPackageR <- function(arg = NULL, deps = TRUE) {
         assert_that(file.exists(r_files[i]),
                     msg = paste0("File: ",r_files[i]," does not exist!"))
         lines <- readLines(r_files[i])
-        lines <- c("---",
+        # do we likely have a yaml header? If not, add one.
+        if (lines[1] != "---") {
+          lines <- c("---",
               paste0("title: ",basename(r_files[i])),
               paste0("author: ", Sys.info()["user"]),
               paste0("date: ", Sys.Date()),
               "---",
               "",
               lines)
-        con <- file(r_files[i])
-        writeLines(lines, con = con, sep = "\n")
-        close(con)
+          con <- file(r_files[i])
+          writeLines(lines, con = con, sep = "\n")
+          close(con)
+        }
       }
       rmarkdown::render(
         input = r_files[i], envir = dataenv,

inst/extdata/tests/rfileTest.R

@@ -1 +1,6 @@
+#' ---
+#' title: Sample report  from R script
+#' author: Greg Finak
+#' date: August 1, 2018
+#' ---
 data <- runif(100)

vignettes/usingDataPackageR.Rmd

@@ -144,6 +144,23 @@ Similarly:
 
 Raw data sets that are stored externally (outside the data package source tree) can be constructed relative to the `project_path()`.
 
+### YAML header metadata for R files and Rmd files.
+
+If your processing scripts are Rmd files, the usual yaml header for rmarkdown documents should be present.
+
+If you have Rmd files, you can still include a yaml header, but it should be commented with `#'` and it should be at the top of your R file. For example, a test R file in the DataPackageR package looks as follows:
+
+```
+#'---
+#'title: Sample report  from R script
+#'author: Greg Finak
+#'date: August 1, 2018
+#'---
+data <- runif(100)
+```
+
+This will be converted to an Rmd file with a proper yaml header, which will then be turned into a vignette and properly indexed in the built package.
+
 
 ## Build the data package.