diff --git a/.gitignore b/.gitignore
old mode 100644
new mode 100755
index bd033e9..c0946a0
--- a/.gitignore
+++ b/.gitignore
@@ -95,4 +95,13 @@ flycheck_*.el
 # network security
 /network-security.data
 
+# html files
+*.html
 
+# images
+*.png
+*.jpg
+*.jpeg
+
+# pdf
+*.pdf
diff --git a/LICENSE b/LICENSE
old mode 100644
new mode 100755
diff --git a/README.org b/README.org
old mode 100644
new mode 100755
index 5ab650f..7007590
--- a/README.org
+++ b/README.org
@@ -1,3 +1,14 @@
-# intro_r
+* A brief introduction to R
 
-Scripts describing simple tasks to learn the first steps to work with data using R programming environment
\ No newline at end of file
+Scripts describing simple tasks to learn the first steps to work with
+data using the R programming environment
+
+** First steps in R
+
+   * [[./script/help_r.R][Asking for help to use R]]
+   * [[./script/integerq_modulo.R][Integer quocient and modulo]]
+   * [[./script/non_stand_eval.R][Non-standard evaluation in R]]
+
+** Subsetting and indexing
+
+   * [[./script/replace_values.R][Build column in table indexing values]]
diff --git a/script/replace_values.R b/script/replace_values.R
old mode 100644
new mode 100755
index 997bb22..879084b
--- a/script/replace_values.R
+++ b/script/replace_values.R
@@ -71,9 +71,9 @@ maior_valor <- function (df, a, b, c, ...) {
     linhas <- nrow(df)
     coluna <- rep(0, times = linhas)
 
-    coluna[a_maior] <- "a"
-    coluna[b_maior] <- "b"
-    coluna[c_maior] <- "c"
+    coluna[a_maior] <- names(df)[[1]]
+    coluna[b_maior] <- names(df)[[2]]
+    coluna[c_maior] <- names(df)[[3]]
 
     df$V1 <- coluna
 
@@ -103,3 +103,19 @@ dfd %>%
                m == 3 ~ names(.)[3],
                TRUE ~ as.character(m)
            ))
+
+#' ## Usando o pacote "datatable"
+
+library(data.table)
+
+class(df)
+
+dt <- setDT(df)
+
+#' Using "apply" to know the greatest value by each row ("1") across
+#' columns
+dt[, great := apply(df, 1, which.max)
+   ][, great := as.character(great)
+     ][, great := c("1" = "a",
+                    "2" = "b",
+                    "3" = "c")[great]]