109  r-quiz

Schlüsselwörter

Aufgaben, Statistik, Prognose, Modellierung, R, Datenanalyse, Regression

109.0.1 Define a variable

Exercise

Define in R the variable age and assign the value 42.

Solution

age <- 42

Note that spaces here are not mandatory, but useful.

109.0.2 Define a variable as a string

Exercise

Define in R the variable name and assign the value me.

Solution

name <- "me"

109.0.3 Define a variable by another variable

Exercise

Define in R the variable name and assign the variable age.

Solution

name <- age

109.0.4 Call a function

Exercise

Ask R what today’s date() is, that is, call a function.

Solution

date()
## [1] "Sat Oct 24 12:28:41 2026"

109.0.5 Define a vector

Exercise

Define in R a vector x with the values 1,2,3 .

Solution

x <- c(1, 2, 3)

109.0.6 Sum up vector

Exercise

Define in R a vector x with the values 1,2,3 . Then sum up its values.

Solution

x <- c(1, 2, 3)
sum(x)
## [1] 6

109.0.7 Vector wise computation

Exercise

Square each value in the vector x.

Solution

x^2
## [1] 1 4 9

109.0.8 Vector wise computation 2

Exercise

Square each value in the vector x and sum up the values.

Solution

sum(x^2)
## [1] 14

109.0.9 Compute the variance

Exercise

Compute the variance of x using basic arithmetic.

Solution

 x <- c(1, 2, 3)

sum((x - mean(x))^2) / (length(x)-1)

 # compare: 
var(x) 
## [1] 1
## [1] 1

109.0.10 Work with NA

Exercise

Define the vector y with the values 1,2,NA. Compute the mean. Explain the results.

Solution

y <- c(1, 2, NA)
mean(y)
## [1] NA

NA (not available, ie., missing data) is contagious in R: If there’s a missing element, R will assume that something has gone wrong and will raise a red flag, i.e, give you a NA back.