fix #4 return a data.frame from ma_abstract with id as first column a…

…nd abstract as 2nd, bump patch ver

DESCRIPTION

@@ -6,7 +6,7 @@ Description: The 'Microsoft Academic Knowledge' API provides programmatic access
 		(<https://academic.microsoft.com/>). Includes methods matching all 'Microsoft
 		Academic' API routes, including search, graph search, text similarity, and
 		interpret natural language query string.
-Version: 0.3.0.9100
+Version: 0.3.1.9100
 Authors@R: person("Scott", "Chamberlain", email = "myrmecocystus+r@gmail.com",
     role = c("aut", "cre"))
 License: MIT + file LICENSE

R/abstract.R

@@ -2,6 +2,7 @@
 #'
 #' @export
 #' @inheritParams ma_search
+#' @return data.frame, with two columns: `Id` and `abstract`
 #' @examples \dontrun{
 #' ma_abstract(query = "Y=2010", count = 10)
 #' ma_abstract(query = "Y=[2010, 2012)", count = 10)
@@ -10,7 +11,10 @@ ma_abstract <- function(query, count = 10, offset = 0, orderby = NULL,
                         model = "latest", key = NULL, ...) {
   out <- ma_evaluate(query, count, offset, orderby, c("Id", "E"), 
     model, key, ...)
-  unname(vapply(out$E, function(z) invabs2abs(jsonlite::fromJSON(z)$IA), ""))
+  tmp <- unname(
+    vapply(out$E, function(z) invabs2abs(jsonlite::fromJSON(z)$IA), ""))
+  tibble::as_tibble(data.frame(Id = out$Id, abstract = tmp, 
+    stringsAsFactors = FALSE))
 }
 
 invabs2abs <- function(x) {