The goal of this tutorial is to learn how to create strings pasting information from different variables. This process can be useful when we need to create a filename from variables or using the index of a loop.
# We can create sentences by pasting individual words
paste("You", "shall", "not", "pass")## [1] "You shall not pass"# However it's not always useful to add spaces between words
# Let's see how to create a date
paste(format(Sys.Date(),"%d"), format(Sys.Date(),"%m"), format(Sys.Date(),"%Y") )## [1] "10 11 2017"# Now we introduce - as separator
paste(format(Sys.Date(),"%d"), format(Sys.Date(),"%m"), format(Sys.Date(),"%Y"), sep = "-" )## [1] "10-11-2017"# Or /
paste(format(Sys.Date(),"%d"), format(Sys.Date(),"%m"), format(Sys.Date(),"%Y"), sep = "/" )## [1] "10/11/2017"# We can paste a character to each element of a vector
my_vector <- LETTERS
my_vector## [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q"
## [18] "R" "S" "T" "U" "V" "W" "X" "Y" "Z"paste(LETTERS, "1")## [1] "A 1" "B 1" "C 1" "D 1" "E 1" "F 1" "G 1" "H 1" "I 1" "J 1" "K 1"
## [12] "L 1" "M 1" "N 1" "O 1" "P 1" "Q 1" "R 1" "S 1" "T 1" "U 1" "V 1"
## [23] "W 1" "X 1" "Y 1" "Z 1"# Or collapse all letters together
paste(LETTERS, collapse = "")## [1] "ABCDEFGHIJKLMNOPQRSTUVWXYZ"# If we want to crate a single string from a vector of words
loftr <- c("You", "shall", "not", "pass")
paste(loftr, collapse = " ")## [1] "You shall not pass"# Paste0 is just a quick way to append strings without separation
paste0("You", "shall", "not", "pass")## [1] "Youshallnotpass"# paste0 is equivalent to paste( , sep="")
paste("You", "shall", "not", "pass", sep = "")## [1] "Youshallnotpass"# This function is very useful when creating filenames
paste0(paste(format(Sys.Date(),"%Y"), format(Sys.Date(),"%m"), format(Sys.Date(),"%d"), sep = "_" ), ".csv")## [1] "2017_11_10.csv"# Sprintf is different from the other options
# Rather than pasting elements we create a single string where elements are introduced
my_day <- format(Sys.Date(),"%d")
my_month <- format(Sys.Date(),"%m")
my_year <- format(Sys.Date(),"%Y")
sprintf("%s-%s-%s.csv",my_year, my_month, my_day)## [1] "2017-11-10.csv"# We use %s to mark the position of the variables that we are going to append
# The same example using paste would be
paste0(paste(my_year, my_month, my_day, sep = "-"),".csv")## [1] "2017-11-10.csv"In this tutorial we have learnt how to create new strings pasting different strings, vector or variables. We have used this examples to create filenames or combine a vector of strings into a single string.