Chapter 2

author: jakwisn

In this quiz some questions might have multiple answers.

1. In code below when R is making copy of object bind to a

a <- c(1, 5, 3, 2)
b <- a
b[[1]] <- 10

In code above when R is making copy of object a

while asigning it to b

while modifying it

2. What is valid name for object in R?

object_

function

1a

_object_

It is posible with all of above after surrounding them with backticks

3. Lets say we have this vector:

x <- c("a","a","bda", "bdb", "ddd", "a")

How to best visualize something called global string pool

ref(x)

ref(x, character = TRUE)

tracemem(x)

untracemem(x)

4. Imagine situation when some non empty, big data frame has binding for 2 names d1 and d2. Select TRUE statement :

By modifying one column in d1 only this column will change list reference, the rest of references won't change

By modifying one row in d1 only this row will change list reference, the rest of references won't change

If we modify one row of d1, whole dataframe will be copied

If we modify one column of d1, whole dataframe will be copied

5. Look at these objects and answer questions

x <- list(a = 1, b = 2, c = 3)
y <- list(x, x, x)
z <- c(1:100000)

Which statements are TRUE

y size is 3 times x's size

obj_size(z) is the same as obj_size(1:1000000)

obj_size(1:1000000) is example of alternative representation

running obj_size(1:1000000) will give really low size (comparable to y)

6. Which statements are TRUE

objects with single binding are modified in place

if two bindings reference to one environment and we modify it by accesing from first name, for the second binding environment won't change

Garbage collector is autonomous and it's behaviour is hard to predict