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In R, all types are vectors. For instance, 5 (number) is a vector of size 1.

  • numeric: 1, 1.3
  • complex: i
  • logical: TRUE, FALSE, T, F
  • NULL, NA (not defined), Inf (infinite)
  • character: "a text", 'a text'
  • vector
  • matrix
  • data.frame (~=an Excel table)
  • list: a vector, with named indexes and that can have different types

Types methods

You have a lot of methods for each type, having this syntax

  • is.xxx(x): return true if x is from the class xxx
  • class(x): return x class
  • mode(x): return x mode
  • identical(x, y): true if x equals y
  • as.xxx(x): convert x to xxx class
  • xxx(...): create an empty vector having the type xxx


# create an empty vector of 3 characters
str <- character(3)
# return true
# character
# character
# try to convert to Date
as.Date(str) # will "fail" since empty