# 1. Hello World!

Here's an R code chunk that prints the text 'Hello world!'.

print("Hello world!")

# (a) Modify the code chunk below to print your name

print("Mayuri Mizuki")

# 2. Creating sequences

We just learned about the c() operator, which forms a vector from its arguments. If we're trying to build a vector containing a sequence of numbers, there are several useful functions at our disposal. These are the colon operator : and the sequence function seq() .

# : Colon operator:

1:10 # Numbers 1 to 10

127:132 # Numbers 127 to 132

# seq function: seq(from, to, by)

seq(1,10,1) # Numbers 1 to 10

seq(1,10,2) # Odd numbers from 1 to 10

seq(2,10,2) # Even numbers from 2 to 10

To learn more about a function, type ?functionname into your console. E.g., ?seq pulls up a Help file with the R documentation for the seq function.

# (a) Use : to output the sequence of numbers from 3 to 12

3:12

# (b) Use seq() to output the sequence of numbers from 3 to 30 in increments of 3

seq(3,30,3)

# (c) Save the sequence from (a) as a variable x , and the sequence from (b) as a variable y . Output their product x*y

x <- 3:12

y <- seq(3,30,3)

x*y

# 3. Cars data

We'll look at data frame and plotting in much more detail in later classes. For a previous of what's to come, here's a very basic example.

For this example we'll use a very simple dataset. The cars data comes with the default installation of R. To see the first few columns of the data, just type head(cars) .

head(cars)

We'll do a bad thing here and use the attach() command, which will allow us to access the speed and dist columns of cars as though they were vectors in our workspace.

attach(cars) # Using this command is poor style.  We will avoid it in the future.

speed

dist

# (a) Calculate the average and standard deviation of speed and distance.

mean(speed) # average of speed

mean(dist) # average of distance

sd(speed) # standard deviation of speed

sd(dist) # standard deviation of distance

We can easily produce a histogram of stopping distance using the qplot function.

qplot(dist, bins=40) # Histogram of stopping distance

# (b) Produce a histogram of stopping distance using the hist function with 10 bins.

hist(dist, breaks = seq(min(dist), max(dist), l=11),col = "pink", main = "Histogram of Stopping Distance",xlab="Distance")

The qplot(x,y,...) function can also be used to plot a vector y against a vector x . You can type ?qplot into the Console to learn more about the basic qplot function.

# (c) Use the qplot(x,y) function to create a scatterplot of dist against speed.

qplot(speed, dist)

# (d) Use the boxplot function to create a boxplot of speed.

boxplot(speed, horizontal = TRUE)