Progress Log 104 (R): Basic Data Types

I’m taking an edX course entitled “Introduction to R for Data Science” and all of the concepts described below come from that course.

Data Types

class() reveals what type a variable is.

  • Logical: otherwise known as boolean values, can either be TRUE or FALSE (note: NA can also be a logical but we will not go into that here).
    • TRUE and FALSE can be abbreviated to T and F. However, it is strongly encouraged to use the full versions.
  • Numeric: The values 2 and 2.5 are called numerics in R. You can perform all sorts of operations on them such as addition, subtraction, multiplication, division, and many more. A special type of numeric is the integer.
    • Integer: is a way to present natural numbers like 1 and 2. To specify that a number is an integer, you add a capital L to them.
      • 2L

Instead of asking for the class of the variable, you can also use the is-dot-functions to see whether variables are actually of a certain type.

  • is.numeric() – used to see if a variable is numeric.
  • is.integer() – used to see if a variable is an integer.
This shows us that integers are numerics, but not all numerics are integers.
  • Character: a string of characters.
  • Other atomic types:
    • double: higher precision
    • complex: complex numbers
    • raw: store raw bytes

Coercion

Coercion changes the type of a variable to another one by using dot functions.

  • as.numeric() – coerces the variable to a numeric. In the example below, we can see that as.numeric(TRUE) coerces the logical to the numeric 1. Whereas as.numeric(FALSE) coerces the logical to the numeric 0.
    • You can even convert characters to numerics.
  • as.character() – coerces the original type of variable to characters.
  • as.integer() – coerces the original type of variable to an integer.
    • In the example below, you can see that "4.5" can be converted to an integer, but loses some information in the conversion.
  • as.logical() – coerces the original type of variable to a logical (boolean).

Coercion is not always possible. The last example below (as.numeric("Hello") returns NA. R doesn’t understand how to transform "Hello" to a numeric and decides to return a Not Available instead.

Practice

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