Row index addition function for #165

.travis.yml

@@ -8,7 +8,6 @@ sudo: true
 warnings_are_errors: false
 
 r:
-  - 3.1
   - 3.2
   - oldrel
   - release
@@ -17,7 +16,6 @@ r:
 
 matrix:
   allow_failures:
-    - r: 3.1
     - r: 3.2
 
 r_binary_packages: 

NAMESPACE

@@ -76,6 +76,7 @@ export(.preds)
 export(.x)
 export(.y)
 export(C5.0_train)
+export(add_rowindex)
 export(boost_tree)
 export(check_empty_ellipse)
 export(decision_tree)

R/adds.R

@@ -0,0 +1,20 @@
+#' Add a column of row numbers to a data frame
+#'
+#' @param x A data frame
+#' @return The same data frame with a column of 1-based integers named `.row`.
+#' @examples
+#' mtcars %>% add_rowindex()
+#' @export
+#' @importFrom dplyr mutate
+add_rowindex <- function(x) {
+  if (!is.data.frame(x)) {
+    stop("`x` should be a data frame.", call. = FALSE)
+  }
+  if (nrow(x) > 0) {
+    x <- dplyr::mutate(x, .row = 1:nrow(x))
+  } else {
+    x$.row <- integer(0)
+  }
+  x
+}
+

tests/testthat/test_adds.R

@@ -0,0 +1,22 @@
+library(dplyr)
+
+# ------------------------------------------------------------------------------
+
+context("adding functions")
+source("helpers.R")
+
+# ------------------------------------------------------------------------------
+
+test_that('adding row indicies', {
+  iris_2 <- iris %>% add_rowindex()
+  expect_true(nrow(iris_2) == 150)
+  expect_true(sum(names(iris_2) == ".row") == 1)
+  expect_true(is.integer(iris_2$.row))
+
+  mtcar_2 <- dplyr::as_tibble(mtcars) %>% dplyr::slice(0) %>% add_rowindex()
+  expect_true(nrow(mtcar_2) == 0)
+  expect_true(sum(names(mtcar_2) == ".row") == 1)
+  expect_true(is.integer(mtcar_2$.row))
+
+  expect_error(as.matrix(mtcars) %>% add_rowindex())
+})