R Lecture Week3

Question 1

whats wrong with this code and why

Answer 1

the single pipe operator is vectorised |
but the if statment is not vectoorised (it will only look at the first element that we get out)

so we should here use the double pipe || operator
we use || to be very clear that we are only taking in a single true or false

for if statements we should remeber to use && and ||

Question 2

why with this ifelse function do we only use the | single

Answer 2

because ifelse is vectorised so we are wanting to return a respose for all 4 elements in the vector

Question 3

1how to generate random numbers between 1 and 1000

2how to make sure you get the same random numbers

Answer 3

1. sample(x = 1:1000, size = 100)

2. set.seed(5)

Question 4

how to check if something is NOT na

Answer 4

!is.na(NA)

Question 5

if( !is.na(as.numeric(input_miles))))

explain that line of code

Answer 5

• tries convert to numeric. if it can true. if it cant, NA.

then check value if its NA. run the code if its not NA