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Answers to the exercises are available here.

**Exercise 1**

Consider 3 vectors, day, month and year:

`year=c(2005:2016)`

month=c(1:12)

day=c(1:31)

Define a list Date such as:

Date=

$year

[1] 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

$month

[1] 1 2 3 4 5 6 7 8 9 10 11 12

$day

[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

**Exercise 2**

write an R statement that will replace the values of year element in Date list for `c(2000:2010)`

.

**Exercise 3**

write an R statement that will delete the value 4 of the month component of the list Date.

**Exercise 4**

Consider a vector x such that:

`x=c(1,3,4,7,11,18,29)`

Write an R statement that will return a list X2 with components of value:

`x*2,x/2,sqrt(x)`

and names `"x*2","x/2","sqrt(x)"`

**Exercise 5**

Consider the X2 list.

Write an R statement that will return a vector:

`2.000000 2.645751 3.316625`

**Exercise 6**

Write an R statement that will return a concatenation M, of Date and X2 lists.

M

$year

[1] 2000 2001 2002 2003 2004 2005 2006 2007 2008

$month

[1] 1 2 3 5 6 7 8 9 10 11 12

$day

[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

[24] 24 25 26 27 28 29 30 31

$`x*2`

[1] 2 6 8 14 22 36 58

$`x/2`

[1] 0.5 1.5 2.0 3.5 5.5 9.0 14.5

$`sqrt(x)`

[1] 1.000000 1.732051 2.000000 2.645751 3.316625 4.242641 5.385165

**Exercise 7**

Write an R statement that will return a sublist N of M, with components year,x*2 and day.

**Exercise 8**

Consider the N list.

Write an R statement that will return:

-the length of x*2 vector in N

-the value of the second element of vector year in N

**Exercise 9**

Consider 3 letters vectors, and 2 numeric vectors:

`A=letters[1:4],B=letters[5:10],C=letters[11:15]`

`D=c(1:10),E=c(20:5)`

Define a list z, with elementes x and y,such that

x is a list with elements A,B,and C;

and y is alist with elements D and E.

**Exercise 10**

Write an R statement that will return:

-the number on third position on the second vector of the first list of z

-the letter on fifth position on the third vector of the second list of z

**Want some extra practice with lists? Please take a look here**

`sum`

, `length`

, `strsplit`

, and `setdiff`

functions.
Answers to the exercises are available here.

**Exercise 1**

If:

```
p <- c(2,7,8),
```

`q <- c("A", "B", "C")`

and

`x <- list(p, q)`

,

then what is the value of `x[2]`

?

a. NULL

b. "A" "B" "C"

c. "7"

```
```**Exercise 2**

If:

`w <- c(2, 7, 8)`

`v <- c("A", "B", "C")`

`x <- list(w, v)`

,

then which R statement will replace "A" in `x`

with "K".

a. ` x[[2]] <- "K" `

b. ` x[[2]][1] <- "K" `

c. ` x[[1]][2] <- "K" `

**Exercise 3**

If `a <- list ("x"=5, "y"=10, "z"=15)`

, which R statement will give the sum of all elements in `a`

?

a. `sum(a)`

b. `sum(list(a))`

c. `sum(unlist(a))`

**Exercise 4**

If `Newlist <- list(a=1:10, b="Good morning", c="Hi")`

, write an R statement that will add 1 to each element of the first vector in `Newlist`

.

**Exercise 5**

If `b <- list(a=1:10, c="Hello", d="AA")`

, write an R expression that will give all elements, except the second, of the first vector of `b`

.

**Exercise 6**

Let `x <- list(a=5:10, c="Hello", d="AA")`

, write an R statement to add a new item z = "NewItem" to the list x.

**Exercise 7**

Consider `y <- list("a", "b", "c")`

, write an R statement that will assign new names "one", "two" and "three" to the elements of y.

**Exercise 8**

If `x <- list(y=1:10, t="Hello", f="TT", r=5:20)`

, write an R statement that will give the length of vector `r`

of `x`

.

**Exercise 9**

Let `string <- "Grand Opening"`

, write an R statement to split this string into two and return the following output:

[[1]]

[1] "Grand"

```
```

`[[2]]`

[1] "Opening"

**Exercise 10**

Let:

`y <- list("a", "b", "c")`

and

`q <- list("A", "B", "C", "a", "b", "c")`

.

Write an R statement that will return all elements of q that are not in y, with the following result:

[[1]]

[1] "A"

```
```[[2]]

[1] "B"

`[[3]]`

[1] "C"

**Want some extra practice with lists? Please take a look here**

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