# Convert String to Lowercase in R

R comes with two functions to convert strings to lowercase: tolower() and casefold() functions. The tolower() function in R converts a string to lowercase. This function takes a single argument, which is the string to be converted. In this guide, we will show how to convert string to lowercase in R.

## Using tolower() Function to Convert String to Lowercase

In this method, we will use the tolower() function to convert string to lowercase in R.

#### Syntax

`tolower(x)`

#### Arguments

• x = string to be converted

### Example 1: Using tolower() to Convert a Single String to Lowercase

```# converting to lowercase
tolower("HELLO WORLD!")```

#### Output

`[1] "hello world!"`

### Example 2: Using tolower() to Convert a Vector of Strings to Lowercase

```# creating a vector
x = c("HELLO", "WORLD!")
# converting to lowercase
tolower(x)```

#### Output

`[1] "hello" "world!"`

### Example 3: Using tolower() to Convert a Column of a Data Frame

```# creating a data frame
df = data.frame(x = c('Fruit', 'Vegetable', 'Dairy'), y = c('APPLE', 'POTATO','CURD'))
df
# converting column y to lowercase
tolower(df\$y)```

#### Output

```x y
1 Fruit APPLE
2 Vegetable POTATO
3 Dairy CURD

[1] "apple" "potato" "curd"```

In the above example, we used the \$ sign to extract the column y from the data frame df.

## Using casefold() Function to Convert String to Lowercase

Unlike the tolower() function, the casefold() function takes two arguments.

#### Syntax

`casefold(x, upper=FALSE)`

#### Arguments

1. x = string to be converted
2. upper = If TRUE then all characters are converted to uppercase. By default, it is FALSE, which converts the characters to lowercase.

### Example 1: Using casefold() to Convert a Single String to Lowercase

```# converting to lowercase
casefold("JUSTICE LEAGUE", upper=FALSE)```

#### Output

`[1] "justice league"`

### Example 2: Using casefold() to Convert a Vector of Strings to Lowercase

```# creating a vector
x = c("JUSTICE", "LEAGUE")
# converting to lowercase
casefold(x,upper=FALSE)```

#### Output

`[1] "justice" "league"`

### Example 3: Using casefold() to Convert a Column of a Data Frame

```# creating a data frame
df = data.frame(x = c('Dominos', 'McDonalds', 'Starbucks'), y = c('PIZZA', 'BURGERS','COFFEE'))
df
# converting to lowercase
tolower(df\$y)```

#### Output

```x y
1 Dominos PIZZA
2 McDonalds BURGERS
3 Starbucks COFFEE

[1] "pizza" "burgers" "coffee"```