We will continue working with the deck of cards example we have seen in lectures. First, let’s load the dataset to RStudio.

## Exercise 1: King of Hearts

### Load data

- Load the dataset and store the data in a data frame called
`deck`

. - The dataset
`cards.csv`

is available at URL: https://nkha149.github.io/stat385-sp2020/files/data/cards.csv.

### Modifying the deck

- We will modify the deck for a game called “King of Hearts” where:
- All kings get the highest value,
`14`

in the deck. - All cards in the
`hearts`

suit get the value of`10`

(except the king of hearts, its value should be 14).

- All kings get the highest value,

Use the following code to check your new deck:

```
## face suit value
## 40 king hearts 14
## 41 queen hearts 10
## 42 jack hearts 10
## 43 ten hearts 10
## 44 nine hearts 10
## 45 eight hearts 10
## 46 seven hearts 10
## 47 six hearts 10
## 48 five hearts 10
## 49 four hearts 10
## 50 three hearts 10
## 51 two hearts 10
## 52 ace hearts 10
```

```
## face suit value
## 1 king spades 14
## 14 king clubs 14
## 27 king diamonds 14
## 40 king hearts 14
```

### Adding the `jackpot`

column

- Now, create a new column called
`jackpot`

in the data frame`deck`

.`jackpot`

takes value of`TRUE`

and`FALSE`

.- For the king of hearts, the value of
`jackpot`

is`TRUE`

. - For all other rows, the value of
`jackpot`

is`FALSE`

.

Your deck should look like this after modifying the value.

```
## face suit value jackpot
## 1 king spades 14 FALSE
## 2 queen spades 12 FALSE
## 3 jack spades 11 FALSE
## 4 ten spades 10 FALSE
## 5 nine spades 9 FALSE
## 6 eight spades 8 FALSE
## 7 seven spades 7 FALSE
## 8 six spades 6 FALSE
## 9 five spades 5 FALSE
## 10 four spades 4 FALSE
## 11 three spades 3 FALSE
## 12 two spades 2 FALSE
## 13 ace spades 1 FALSE
## 14 king clubs 14 FALSE
## 15 queen clubs 12 FALSE
## 16 jack clubs 11 FALSE
## 17 ten clubs 10 FALSE
## 18 nine clubs 9 FALSE
## 19 eight clubs 8 FALSE
## 20 seven clubs 7 FALSE
## 21 six clubs 6 FALSE
## 22 five clubs 5 FALSE
## 23 four clubs 4 FALSE
## 24 three clubs 3 FALSE
## 25 two clubs 2 FALSE
## 26 ace clubs 1 FALSE
## 27 king diamonds 14 FALSE
## 28 queen diamonds 12 FALSE
## 29 jack diamonds 11 FALSE
## 30 ten diamonds 10 FALSE
## 31 nine diamonds 9 FALSE
## 32 eight diamonds 8 FALSE
## 33 seven diamonds 7 FALSE
## 34 six diamonds 6 FALSE
## 35 five diamonds 5 FALSE
## 36 four diamonds 4 FALSE
## 37 three diamonds 3 FALSE
## 38 two diamonds 2 FALSE
## 39 ace diamonds 1 FALSE
## 40 king hearts 14 TRUE
## 41 queen hearts 10 FALSE
## 42 jack hearts 10 FALSE
## 43 ten hearts 10 FALSE
## 44 nine hearts 10 FALSE
## 45 eight hearts 10 FALSE
## 46 seven hearts 10 FALSE
## 47 six hearts 10 FALSE
## 48 five hearts 10 FALSE
## 49 four hearts 10 FALSE
## 50 three hearts 10 FALSE
## 51 two hearts 10 FALSE
## 52 ace hearts 10 FALSE
```

### Function `draw()`

- Write a function
`draw()`

that randomly draws**4 cards from the deck WITHOUT replacement**and compute the sum of the 4 cards that were drawn.**Input**: no input provided.**Output**: a number representing the sum of values of the 4 cards drawn.

Use the following code to test your function:

`## [1] 22`

`## [1] 36`

`## [1] 29`

`## [1] 31`

### Function `win_jackpot()`

- This is a strange game where a person can win a jackpot through 3 possible ways:
- Getting a king of hearts in the 4 cards drawn.
- OR getting 4 cards from the same suit.
- OR getting 4 cards with the same face.

- Write a function
`win_jackpot()`

that:- randomly draws 4 cards from the deck WITHOUT replacement
**print out the 4 cards**using the`print()`

function- and returns
`TRUE`

if the 4 cards drawn satisfying**one of the above conditions**,`FALSE`

otherwise.

**Hint**: You might want to take a look at the`unique()`

function to test the 2nd and 3rd conditions.

```
## face suit value jackpot
## 6 eight spades 8 FALSE
## 26 ace clubs 1 FALSE
## 23 four clubs 4 FALSE
## 18 nine clubs 9 FALSE
```

`## [1] FALSE`

```
## face suit value jackpot
## 10 four spades 4 FALSE
## 6 eight spades 8 FALSE
## 8 six spades 6 FALSE
## 1 king spades 14 FALSE
```

`## [1] TRUE`

```
## face suit value jackpot
## 22 five clubs 5 FALSE
## 1 king spades 14 FALSE
## 48 five hearts 10 FALSE
## 40 king hearts 14 TRUE
```

`## [1] TRUE`

```
## face suit value jackpot
## 13 ace spades 1 FALSE
## 52 ace hearts 10 FALSE
## 39 ace diamonds 1 FALSE
## 26 ace clubs 1 FALSE
```

`## [1] TRUE`

### Running simulation on `win_jackpot()`

Now, we want to estimate the probability of winning the jackpot in “King of Hearts”. How do we do that? We can do so using simulation studies, that is running the `win_jackpot()`

function many many times and record the number of times we win. In this example, the number of simulations is 10000.

**<!!!>BEWARE<!!!>**: You need to change your `win_jackpot()`

function before progressing to the next part.

- First, write a new function called
`win_jackpot2()`

:- Copy the code from your original
`win_jackpot()`

function. - Remove the
`print()`

statement from the code. - Test your
`win_jackpot2()`

function:

- Copy the code from your original

`## [1] TRUE`

- Use the following code to run the simulation studies:
- Make sure you copy and paste! If you retype the code, remember
`win_jackpot2()`

!!! Missing the 2 will cost you heavily!

- Make sure you copy and paste! If you retype the code, remember

- Now, use
`results`

to compute the estimated probability of winning a jackpot. Your answer should be**0.0886**.

## Exercise 2: 2015 Flight Delays and Cancellations Data

Next, we take a quick look at the 2015 Flight Delays and Cancellations Data provided by the U.S. Department of Transportation. This is a huge dataset availalbe on Kaggle. But for us, we will only take a look at flights **flying out** from O’Hare International Airport (ORD) in January, 2015.

### Load data

- I have filtered out the data specific to O’Hare and stored it in
`ohare_jan.csv`

. You can TRY load the data from the following URL: https://nkha149.github.io/stat385-sp2020/files/data/ohare_jan.csv.- You probably will get an error!
- What do you do?
- Try downloading the file and load the data through the RStudio interface instead!

- Save the data into a data frame named
`flights`

.

### Counting

- Count how many flights departed from ORD in January, 2015.
- Your answer should be
**23484**.

- Your answer should be
- Count how many flights departed from ORD that were American Airlines flights (AA) in January, 2015.
- Your answer should be
**3899**.

- Your answer should be
- Look at function
`table()`

. Use it to get a summary of the number of flights flying out from ORD for each airline in January, 2015.- Your result should look as followed:

```
##
## AA AS B6 DL EV F9 MQ NK OO UA US VX
## 3899 100 170 569 3767 283 5655 767 3181 4383 634 76
```