R Strings - gizotso/R GitHub Wiki

Strings : vector with mode character

as.character(), is.character()

  • str = "North Face": [1] "North Face"
  • str = c("tic", "tac toe 3D"): [1] "tic" "tac toe 3D"
    • length(str): nb elements ## [1] 2 -nchar(str): nb char in each string ## [1] 3 10

Special char vectors : letters, LETTERS

> letters
[1] "a" "b" "c" "d" "e" ... "y" "z"

Concatenate

  • cat: concatenate and print
  • paste : concatenate vectors after converting to character
c('North', 'Face')             ##[1] "North" "bar"
paste('North', 'Face')         ##[1] "North Face"
paste0('North', 'Face')        ##[1] "NorthFace"
paste('North', 'Face', sep='') ##[1] "NorthFace"

> s = c('North', 'Face')
[1] "North" "Face"
> paste(x, collapse='-')
[1] "North-Face"

paste("Today is", date())  ##[1] "Today is Wed Sep 13 20:40:11 2017"

paste(1:12) # same as as.character(1:12)

paste('file',c(1:5), sep='_')
[1] "file_1" "file_2" "file_3" "file_4" "file_5"

y = paste("y", 1:5, sep="")
[1] "y1" "y2" "y3" "y4" "y5"
# join a vector into a string
paste(letters, collapse='')
[1] "abcdefghijklmnopqrstuvwxyz"

x = 1; y = 2
toString(c(x,y))
[1] "1, 2"

iteration=  4
cat('iteration= ', i, '\n')
iteration=  4

wd=getwd()
cat("Current working dir: ", wd)

Print

  • print:
  • sprintf: C-style formatting function
  • message: same formatting that Error/Warning message
sprintf("Current working dir: %s", wd)
[1] "Current working dir: C:/Users/family/Documents"

cat(sprintf("Current working dir: %s\n", wd))
Current working dir: C:/Users/family/Documents

print(paste("Current working dir: ", wd))
[1] "Current working dir:  C:/Users/family/Documents

Split: strsplit()

strsplit("foo, bar",", ") # returns a list

[[1]]
[1] "foo" "bar"

unlist(strsplit("foo, bar",", "))
[1] "foo" "bar"

strsplit("a.b.c", "[.]") #returns a list
	# [[1]]
	# [1] "a" "b" "c"
unlist(strsplit("a.b.c", "[.]")) ##[1] "a" "b" "c"

txt = " blue
red
x"
## [1] " blue\nred\nx"
unlist(strsplit(txt, "[\n]"))
##[1] " blue" "red"   "x"

Substring

substring('hello world', 7, 11) # start pos, <end pos>
[1] "world"

substring('hello world',1, 1:3) # vectorial substring
[1] "h"   "he"  "hel"

substring("hello",2,3)         ##[1] "el"
substring("Hello",1:3,3)       ##[1] "Hel" "el"  "l"
s=substring("Hello", 1:5, 1:5) ##[1] "H" "e" "l" "l" "o"   s[2] -> [1] "e"

Substitutions

Substitutions : sub et gsub (global: all occurences)

s = 'un pour tous et tous pour un'
sub('un',1,s)
[1] "1 pour tous et tous pour un"
gsub('un',1,s)
[1] "1 pour tous et tous pour 1"

String Translation

> chartr("abcd", "1234", 'a cat')
[1] "1 31t"

Regular expressions

escape char \

cit <- "She said: \"Double quotes can be included in R’s strings.\""
## [1] "She said: \"Double quotes can be included in R’s strings.\""
cat(cit, "\n")
## She said: "Double quotes can be included in R’s strings."

cit <- 'Double quotes " delimitate R\'s strings.'  
## [1] "Double quotes \" delimitate R's strings."
cat(cit)                                           
## Double quotes " delimitate R's strings.

Quoting

quote(expr) quote simply returns its argument. The argument is not evaluated and can be any R expression

x = 2
quote(x+2)           ## x + 2        mode:"call"
deparse(quote(x+2))  ## [1] "x + 2"

e = quote(`foo bar`)         ## `foo bar`    mode:"name"
deparse(e)                   ## [1] "foo bar"
deparse(e, control = "all")  ## [1] "quote(foo bar)"

e = quote(`foo bar` + 1)     ## `foo bar` + 1     mode:"call"
deparse(e)                   ## [1] "foo bar + 1"
deparse(e, control = "all")  ## [1] "quote(foo bar)"
⚠️ **GitHub.com Fallback** ⚠️