RinAction - R Functions - Character Functions

gistfile1.r

###########################################
##           Character Function          ##
###########################################

# Number of characters
x <- c("ab", "cde", "fghij")
a <- length(x)
b <- nchar(x[3]) # returns 5

# substring
x <- "abcdef"
a <-substr(x,2,4) # returns "bcd"
substr(x,2,4) <- "22222" # returns "a222ef"

# search
grep("A", c("b","A","c"), fixed=TRUE, ignore.case=FALSE) # returns index

# replace
sub("\\s",".","Hello There") # replace whitespace with .

# split - 
y <- strsplit("abc", "") # returns a 1-component 3-element list containing "a" "b" "c"
y
unlist(y)[2] # returns "b"
sapply(y,"[",2) # returns "b"



# concatenate strings
paste("x", 1:3, sep="") 
paste("TOday is", date())

# Uppercase
toupper("abc")

# Lowercase
tolower("ABC")

#############################
### Escape Characters #######
#############################

# \n      -- new line
# \s      -- white space
# \t      -- tab
# \'      -- single quote
# \b      -- backspoace

name <- "Bob"
cat("Hello", name, "\b.\n","Isn\'t R", "\t", "GREAT?\n")

# Note: When cat concatenates objects for output, it separates each by a space. 
# That’s why you include the backspace (\b) escape character before the period.