R Language: Atomic types: Logical

A LOT of R code examples focus on advanced tasks. Only a FEW focus on the basics, assuming everyone knows everything about the core concepts. Honestly, the foundations aren't as exciting to write about. But I've encountered a lot of R users who don't have a workable grasp of beginning concepts. So let's spend a bit of time building up a ground-level understanding of R.

R has six atomic data types: logical, integer, real, complex, string, character, and raw. It has six data structures: vector, list, matrix, array, data.frame, and factor.

Atomic Data Types: Logical

Let's take a quick look at logical data types. Logical data types are TRUE or FALSE. For example:

I.am.logical <- TRUE

is.logical(I.am.logical)

        

This code creates a vector and places one TRUE value in the vector. Notice I said "vector" instead of "variable." In R, a simple variable is called a vector because it can contain multiple values. Is that confusing? Yes. But when you learn about vectors in R, the name makes sense.

Here's how to test for the typof( ) logical. Use is.logical( ) to see if a vector is of type logical. FALSE and TRUE are logical values. False and True are NOT logical values (at least, not in R)

> is.logical(FALSE)
[1] TRUE

> is.logical(false) # FALSE, not false. TRUE, not true (or True)
Error: object 'false' not found

> is.logical(True)
Error: object 'True' not found

> is.logical(1) # 1 is an integer. Not logical
[1] FALSE

> as.numeric(TRUE) # although the inverse sort of works
[1] 1
        

Oh - and sometimes "1" and "0" are logical values.

When you have logical values, you can perform AND, OR, NAND, and NOR operations...

> TRUE & FALSE # use & for and. Caution: & is different than &&
[1] FALSE

> TRUE | FALSE # use | for or. Caution: | is different than ||
[1] TRUE

> ! FALSE # use ! for negate
[1] TRUE
        

Remember talking about vectors instead of variables? Here's an example of a vector with multiple logical values.

> I.am.logical <- c(TRUE,TRUE,FALSE)

> any(I.am.logical)
[1] TRUE

> all(I.am.logical)
[1] FALSE
        

Now try any( ) and all( ) with the multi-value vector. These are really simple tools to examine the state of a vector.

Want more? R for Data Science shows this type of stuff every week. Here's a sample...

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