diff --git a/r.html.markdown b/r.html.markdown
index e90d5a97..e42b1f5e 100644
--- a/r.html.markdown
+++ b/r.html.markdown
@@ -4,6 +4,7 @@ contributors:
- ["e99n09", "http://github.com/e99n09"]
- ["isomorphismes", "http://twitter.com/isomorphisms"]
- ["kalinn", "http://github.com/kalinn"]
+ - ["mribeirodantas", "http://github.com/mribeirodantas"]
filename: learnr.r
---
@@ -405,7 +406,7 @@ mat
# [2,] 2 5
# [3,] 3 6
# Unlike a vector, the class of a matrix is "matrix", no matter what's in it
-class(mat) # => "matrix"
+class(mat) # => "matrix" "array"
# Ask for the first row
mat[1,] # 1 4
# Perform operation on the first column
@@ -478,9 +479,10 @@ class(students[,3]) # "factor"
nrow(students) # 6
ncol(students) # 3
dim(students) # 6 3
-# The data.frame() function converts character vectors to factor vectors
-# by default; turn this off by setting stringsAsFactors = FALSE when
-# you create the data.frame
+# The data.frame() function used to convert character vectors to factor
+# vectors by default; This has changed in R 4.0.0. If your R version is
+# older, turn this off by setting stringsAsFactors = FALSE when you
+# create the data.frame
?data.frame
# There are many twisty ways to subset data frames, all subtly unalike