Learn R: Common character functions you need to know

   

      R comes with many built-in functions, I am going to cover the most common built-in character functions you might use daily in this post. These functions are coming with the base package and you do not need to add/install any packages to use them.

How to get substring of a text?

substr(txt, start, end)

text <- 'Today is a great day to learn R'
firstfive <- substr(text,1,5)
firstfive

[1] "Today"
> 

R-Fiddle

How to convert string to upper or lower cases?

 

toupper(txt)

tolower(txt)

 

[text <- 'Today is a great day to learn R'

toupper(text)
tolower(text)

[[1] "TODAY IS A GREAT DAY TO LEARN R"
[1] "today is a great day to learn r"
>

R-Fiddle

How to split string and create a list?

 

strsplit(text, character)

 

[text <- 'Today is a great day to learn R'
list <- strsplit(text,' ')
class(list)

[[1] "Today" "is"    "a"     "great" "day"   "to"    "learn" "R"   
[1] "list"
> 

R-Fiddle

How to convert list to array/vector?
 

unlist(obj)

 

[text <- 'Today is a great day to learn R'
list <- strsplit(text,' ')
arr <- unlist(list)
print(arr)

[[1] "Today" "is"    "a"     "great" "day"   "to"    "learn" "R" 
> 

R-Fiddle

How to seach in array?

 

grep(pattern, object, ignore.case=False, fixed=False)

Fixed argument needs to be False if you want to use regex pattern
 

[text <- 'Today is a great day to learn R'
list <- strsplit(text,' ')
arr <- unlist(list)
grep('day', arr, fixed=T)

[[1] 1 5 
> 

R-Fiddle

How to replace item/s in an array?

 

sub(pattern, replacement, target, ignore.case=False, fixed=False)

Fixed argument needs to be False if you want to use regex pattern
 

text <- 'Today is a great day to learn R'
sub('a great', 'the', text)

[[1] "Today is the day to learn R" 
> 

R-Fiddle

How to Concatenate strings?

paste(obj, sep="")
 

text <- 'Today is a great day to learn R'
list <- strsplit(text,' ')
arr <- unlist(list)
paste(arr,' ', sep=' ')
paste('Today is', date())

[[1] "Today  " "is  "    "a  "     "great  " "day  "   "to  "    "learn  "
[8] "R  "    
[1] "Today is Fri Sep  8 12:55:01 2017"
> 

R-Fiddle