Merge branch 'f-#121-doc-print'. Fixes #121.

- `print.tbl_df()` gains `n_extra` method and will have the same interface as `trunc_mat()` from now on.
- Added more examples for `print.tbl_df()`, now using data from `nycflights13` instead of `Lahman`.

DESCRIPTION

@@ -24,7 +24,7 @@ Suggests:
     withr,
     knitr (>= 1.5.32),
     rmarkdown,
-    Lahman (>= 3.0.1),
+    nycflights13,
     microbenchmark
 LinkingTo: Rcpp
 LazyData: yes

R/glimpse.R

@@ -19,10 +19,7 @@
 #' @export
 #' @examples
 #' glimpse(mtcars)
-#'
-#' if (require("Lahman")) {
-#'   glimpse(Lahman::Batting)
-#' }
+#' glimpse(nycflights13::flights)
 glimpse <- function(x, width = NULL, ...) {
   UseMethod("glimpse")
 }

R/tbl-df.r

@@ -10,8 +10,8 @@ as.data.frame.tbl_df <- function(x, row.names = NULL, optional = FALSE, ...) {
 
 #' @rdname formatting
 #' @export
-print.tbl_df <- function(x, ..., n = NULL, width = NULL) {
-  print(trunc_mat(x, n = n, width = width))
+print.tbl_df <- function(x, ..., n = NULL, width = NULL, n_extra = NULL) {
+  print(trunc_mat(x, n = n, width = width, n_extra = n_extra))
   invisible(x)
 }
 

R/utils-format.r

@@ -9,6 +9,10 @@
 #'   \code{getOption("width")}; the latter displays only the columns that
 #'   fit on one screen. You can also set \code{options(tibble.width = Inf)} to
 #'   override this default and always print all columns.
+#' @param n_extra Number of extra columns to print abbreviated information for,
+#'   if the width is too small for the entire tibble. If \code{NULL}, the
+#'   default, will print information about at most \code{tibble.max_extra_cols}
+#'   extra columns.
 #' @seealso \link{tibble-package}
 #' @keywords internal
 #' @examples
@@ -19,6 +23,8 @@
 #' print(as_tibble(mtcars), n = 3)
 #' print(as_tibble(mtcars), n = 100)
 #'
+#' print(nycflights13::flights, n_extra = 2)
+#' print(nycflights13::flights, width = Inf)
 #' @name formatting
 NULL
 

tests/testthat/test-trunc-mat.R

@@ -1,5 +1,14 @@
 context("Truncated matrix")
 
+test_that("interface of print() identical to trunc_mat()", {
+  print_arg_names <- names(formals(print.tbl_df))
+  print_arg_names_without_ellipsis <- setdiff(print_arg_names, "...")
+
+  trunc_mat_arg_names <- names(formals(trunc_mat))
+
+  expect_equal(print_arg_names_without_ellipsis, trunc_mat_arg_names)
+})
+
 test_that("print() returns output invisibly", {
   expect_output(ret <- withVisible(print(as_tibble(mtcars))))
   expect_false(ret$visible)