R Strings

R language strings can be represented using a pair of single quotes ' ' or a pair of double quotes " ".

• Single quotes can contain double quotes.

• Single quotes cannot contain single quotes.

• Double quotes can contain single quotes.

• Double quotes cannot contain double quotes.

The following examples demonstrate the use of string concatenation:

a <-　Use single quotes
print(a)
b <-　Use double quotes
print(b)
c <-　Double quotes can contain single quotes (')
print(c)
d <-　'Double quotes can be included in single quotes (\")'
print(d)

The output of the above code is:

[1]) "Use single quotes"
[1]) "Use double quotes"
[1]) "Single quotes can be included in double quotes ('')"
[1]) "Double quotes can be included in single quotes (\")"

String operations

Let's take a look at some built-in functions of R language for string operations.

paste() function

The paste() function is used to concatenate strings using a specified separator, the default separator is space.

Syntax Format:

paste(..., sep = " ", collapse = NULL)

Parameter Description:

• ...: String list

• sep: Separator, default is space

• collapse: Concatenate two or more string objects based on element correspondence, then use collapse to connect the connector after the string is connected

a <-　"Google"
b <-　'w3codebox'
c <-　"Taobao"
print(paste(a, b, c))
print(paste(a, b, c, sep = ""))-"))
print(paste(letters[1:6],1:6, sep = "", collapse = "=")
paste(letters[1:6],1:6, collapse = ".")

The output of the above code is:

[1]) "Google w3codebox Taobao"
[1]) "Google-w3codebox-Taobao"
[1]) "a1=b2=c3=d4=e5=f6"
[1]) "a　1.b　2.c　3.d　4.e　5.f　6"

format() function

The format() function is used to format strings, and format() can act on strings or numbers.

Syntax Format:

format(x, digits, nsmall, scientific, width, justify = c("left", "right", "centre", "none"))

Parameter Description:

• x: Input for vector

• digits: The number of digits to display

• nsmall: The minimum number of digits to display after the decimal point

• scientific: Set scientific notation

• width: Display the minimum width by filling spaces at the beginning

• justify: Set position, the display can be left, right, center, etc.

# Display　9　digits, the last digit rounded
result  <-　format(23.123456789, digits =　9)
print(result)
# Use scientific notation to display
result  <-　format(c(6,　13.14521)), scientific = TRUE)
print(result)
#  Minimum display of decimal points to the right　5　spaces, fill with 0 if none
result  <-　format(23.47,  nsmall =　5)
print(result)
#  Convert numbers to strings
result  <-　format(6)
print(result)
#  Width is　6　spaces, add spaces at the beginning if not enough
result  <-　format(13.7,  width =　6)
print(result)
#  Left-align string
result  <-　format("w3codebox,  width =　9,  justify =  "l")
print(result)
#  Centered display
result  <-　format("w3codebox,  width =　10,  justify =  "c")
print(result)

The output of the above code is:

[1]  "23.1234568"
[1]  "6.000000e+00"  "1.314521e+01"
[1]  "23.47000"
[1]  "6"
[1]  "　　13.7"
[1]  "w3codebox  "
[1]  "  "w3codebox  "

nchar() Function

The nchar() function is used to count the length of a string or a numeric list.

Syntax Format:

nchar(x)

Parameter Description:

• x: Vector or string

result  <-　nchar("Google  w3codebox Taobao)
print(result)

The output of the above code is:

[1]　20

toupper() & tolower() functions

toupper() & tolower() functions are used to convert the letters of a string to uppercase or lowercase.

Syntax Format:

toupper(x)
tolower(x)

Parameter Description:

• x: Vector or string

# Convert to uppercase

result  <-　toupper("w3codebox)
print(result)
#  Convert to lowercase
result  <-　tolower("w3codebox)
print(result)

The output of the above code is:

[1]  "w3codebox
[1]  "w3codebox

substring() function

The substring() function is used to extract strings.

Syntax Format:

substring(x,first,last)

Parameter Description:

• x: Vector or string

• first: Starting cutting position

• last: End of the cutting position

#  From the　2　bit cut to the　5　bit
result  <-　substring("w3codebox　2,　5)
print(result)

The output of the above code is:

[1]  "hooo"