r strings

R Strings

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R Strings

Strings are used for storing text. In R, when you enclose a value in either single or double quotes, it is considered a string. R internally stores all strings within double quotes, even if they are initially created with single quotes.

Rules to write R Strings

Here are the guidelines for creating a valid string in R programming:

  • You must use either single or double quotes to encapsulate a string value, like str1 <- 'Hello' or str2 <- "Hello".
  • Since single and double quotes are the special characters denoting an R string, inserting them into a string requires careful handling.
  • To incorporate a single quote within a string, enclose it with double quotes, as in str1 = "Jim's book.".
  • For including a double quote within a string, use single quotes around it, for example, str1 = 'Jim says, "Hello World"'.
  • Single or double quotes can be included at the beginning or end of a string value as they are, such as str1 = "'Hello".

R String Operations

  • R – Assign a String to a Variable
  • R – Multiline String
  • R – Find length of String
  • R – Check a String
  • R – Concatenate or Combine Strings
  • R – Format Numbers & Strings 
  • R – Extract String or Substring of a String
  • R – Convert String to Upper-case
  • R – Convert String to Lower-case

R – Assign a String to a Variable

Assigning a string to a variable is done with the variable followed by the <- or = operator and the string:

Example:

str <- "Hello world"
str1 = "Hello world1"
# print the value of str
str 
str1

#output:
[1] "Hello world"
[1] "Hello world1"

R – Multiline String

We can assign a multiline string to a variable.

Example:

str <- "Hello,
I am Jim,
R programming is interesting
I love it very much."
# print the value of str
str 

#output:
[1] "Hello,\nI am Jim,\nR programming is interesting\nI love it very much."

R – Find length of String

We first initialize a variable with a String value and then we will find its length using nchar(string) function. When dealing with numbers nchar automatically type casts number to character by using nchar(num).

Example:

str = 'Hello World!'
length.str = nchar(str)
print ("length.str")
print (length.str)

num = 12345
length.num = nchar(num)
print ("length.num")
print (length.num)

#output:
[1] "length.str"
[1] 12

[1] "length.num"
[1] 5

R – Check a String

We will use the grepl() function to check if one or more characters are present in a string:

Example:

str <- "Hello World!"
grepl("H", str)
grepl("World", str)
grepl("Z", str)

#output:
[1] TRUE
[1] TRUE
[1] FALSE

R – Concatenate or Combine Strings

Syntax:

paste(…, sep="", collapse=NULL)

pasteis the keyword
…input strings separated by comma.
sepis a character that acts as a separator
collapseis an optional character to separate the results

Example:

str1 <- 'Hello'
str2 <- 'World!'
str3 <- 'I am'
str4 <- 'Jim'

# concatenate two strings
result1 <- paste(str1,str2)
print ("result1")
print (result1)

# concatenate two strings with no separator
result2 <- paste(str1,str2,sep="")
print ("result2")
print (result2)

# concatenate multiple string
result3 = paste(str1,str2,str3,str4,sep="-")
print ("result3")
print (result3)

#output:
[1] "result1"
[1] "Hello World!"

[1] "result2"
[1] "HelloWorld!"

[1] "result3"
[1] "Hello-World!-I am-Jim"

R – Format Numbers & Strings 

String formatting in R is done with the sprintf() and format() function.

Example – sprintf():

# Create two variables with values
x <- 50
y <- 2.87901

# Format a string with the two variable values
result <- sprintf("The number is %d, and y is %.2f.", x, y)

# Print the result
print(result)

#output:
[1] "The number is 50, and y is 2.88."

Example – format():

# Total number of digits displayed. Last digit rounded off.
result <- format(11.123456789, digits = 9)
print(result)

# Display numbers in scientific notation.
result <- format(c(5, 11.12531), scientific = TRUE)
print(result)

# The minimum number of digits to the right of the decimal point.
result <- format(21.37, nsmall = 5)
print(result)

# Format treats everything as a string.
result <- format(22)
print(result)

# Numbers are padded with blank in the beginning for width.
result <- format(11.2, width = 5)
print(result)

# Left justify strings.
result <- format("Good", width = 7, justify = "l")
print(result)

# Justfy string with center.
result <- format("Good", width = 7, justify = "c")
print(result)

#output:
[1] "11.1234568"
[1] "5.000000e+00" "1.112531e+01"
[1] "21.37000"
[1] "22"
[1] " 11.2"
[1] "Good   "
[1] " Good  "

R – Extract String or Substring of a String

Syntax:
substring(c, first, last)

Example:

#Get Substring from a String with first and last positions
str <- 'Welcome to  R tutorial'
subStr1 <- substring(str, 13, 19)
print (subStr1)

#Get Substring from a String Without last positions
subStr2 <- substring(str, 13)
print (subStr2)

#output:
[1] "R tutor"
[1] "R tutorial"

R – Convert String to Upper-case

To convert Strings to upper-case is done using toupper() function.

Example:

str <- 'Hello World'
result <- toupper(str)
print(result)

#output
[1] "HELLO WORLD"

R – Convert String to Lower-case

To convert Strings to lower-case is done using tolower() function.

Example:

str <- 'HELLO WORLD, good job!'
result <- tolower(str)
print(result)

#output:
[1] "hello world, good job!"

Conclusion

In this R Tutorial, we have learned R Strings Operations.

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