A very important concept in programming is variable
assignment. In R there are several assignment operators available :
->>. For the sake of simplicity
we will use the
<- assignment operator throughout the
Let us assign two numerical values to variables denoted as
x <- 25 y <- 11
R will not print out anything to the console. However, we now have
assigned the value 25 to the variable
x and the value 11 to
y. These variables are now stored in our
interactive workspace, referred to as global
environment. The idea of environments, by which a set of names is
associated to a set of values, is quite fundamental, however, a sound
discussion on this topic is beyond the scope of this section. The
companion website for Advanced R, a book by Hadley Wickham, offers a
nice introduction on this topic (here).
We can ask R which variables are currently stored in our workspace by
##  "x" "y"
We can reuse these values by simply using the variable names in our arithmetic calculations.
##  25
##  11
x + y
##  36
Exercise: Calculate the points of intersect with the x-axis of the following function in R: \(f(x)=x^2+3x-4\). Remember that you need the (Quadratic formula) (or formerly called p-q-formula) for this purpose. Use variables to store the points of intersect!
### your code here
b <- 3 c <- -4 # solve quadratic formula y=ax^2+bx+c with a=1 # in p-q-formula: b=p and c=q x1 <- -(b / 2) + sqrt((b / 2)^2 - c) x2 <- -(b / 2) - sqrt((b / 2)^2 - c) x1 x2
##  1
##  -4
The E-Learning project SOGA-R was developed at the Department of Earth Sciences by Kai Hartmann, Joachim Krois and Annette Rudolph. You can reach us via mail by soga[at]zedat.fu-berlin.de.
Please cite as follow: Hartmann, K., Krois, J., Rudolph, A. (2023): Statistics and Geodata Analysis using R (SOGA-R). Department of Earth Sciences, Freie Universitaet Berlin.