Learning R data types – Vector

Dylan Wan R Programming

A vector in R is like a column in Excel or a column in a database table.

By using the following command, I am adding values to cells in a column,

X = c(1,2,3)

R_vector

Note:

I like to think in this way although it is not exactly true.

But it is easier to understand R vector if you are coming with a background from a database designer or an Excel user.

Aggregates

sum(X) is for calculating the total

mean(X) is for calculating the mean.

Here is a comparison of some aggregate functions available in Oracle database and what are their equivalent in R:

  • SUM -> sum
  • AVG – mean
  • MAX -> max
  • MIN->min
  • COUNT-> length
  • MEDIAN -> median

Order By

Here is a good example: Operations on vectors

> a = c(2,4,6,3,1,5)
> b = sort(a)
> c = sort(a,decreasing = TRUE)
> a
[1] 2 4 6 3 1 5
> b
[1] 1 2 3 4 5 6
> c
[1] 6 5 4 3 2 1

This is similar to issue an Order by clause.

Expression / mass update

Once you have the data in a vector, you can apply operations to every element in the vector using a single command:

> a <- c(1,2,3,4)
> a
[1] 1 2 3 4
> a + 5
[1] 6 7 8 9
> a - 10
[1] -9 -8 -7 -6
> a*4
[1]  4  8 12 16
> a/5
[1] 0.2 0.4 0.6 0.8

See Also: Basic Operations

Expression on more than one columns

> a=c(1,2,3)
> b=c(10,20,30)
> c=a+b
> c
[1] 11 22 33
>

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