R Convert Data Frame to Uppercase – All Character String Columns (Example Code)

data(iris)                                    # Load data
iris$Species <- as.character(iris$Species)    # Convert factors to character string
head(iris)                                    # Have a look at first rows
#   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# 1          5.1         3.5          1.4         0.2  setosa
# 2          4.9         3.0          1.4         0.2  setosa
# 3          4.7         3.2          1.3         0.2  setosa
# 4          4.6         3.1          1.5         0.2  setosa
# 5          5.0         3.6          1.4         0.2  setosa
# 6          5.4         3.9          1.7         0.4  setosa

data(iris) # Load data iris$Species <- as.character(iris$Species) # Convert factors to character string head(iris) # Have a look at first rows # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 setosa # 2 4.9 3.0 1.4 0.2 setosa # 3 4.7 3.2 1.3 0.2 setosa # 4 4.6 3.1 1.5 0.2 setosa # 5 5.0 3.6 1.4 0.2 setosa # 6 5.4 3.9 1.7 0.4 setosa

iris_new <- data.frame(lapply(iris,           # Changing iris character to uppercase
                              function(variables) {
                                if (is.character(variables)) {
                                  return(toupper(variables))
                                } else {
                                  return(variables)
                                }
                              }),
                       stringsAsFactors = FALSE)
head(iris_new)                                # Show first rows again
#   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# 1          5.1         3.5          1.4         0.2  SETOSA
# 2          4.9         3.0          1.4         0.2  SETOSA
# 3          4.7         3.2          1.3         0.2  SETOSA
# 4          4.6         3.1          1.5         0.2  SETOSA
# 5          5.0         3.6          1.4         0.2  SETOSA
# 6          5.4         3.9          1.7         0.4  SETOSA

iris_new <- data.frame(lapply(iris, # Changing iris character to uppercase function(variables) { if (is.character(variables)) { return(toupper(variables)) } else { return(variables) } }), stringsAsFactors = FALSE) head(iris_new) # Show first rows again # Sepal.Length Sepal.Width Petal.Length Petal.Width Species # 1 5.1 3.5 1.4 0.2 SETOSA # 2 4.9 3.0 1.4 0.2 SETOSA # 3 4.7 3.2 1.3 0.2 SETOSA # 4 4.6 3.1 1.5 0.2 SETOSA # 5 5.0 3.6 1.4 0.2 SETOSA # 6 5.4 3.9 1.7 0.4 SETOSA