Objects

Object names

You can choose almost any name you like for an object, as long as the name does not begin with a number or a special character like +, -, *, /, ^, !, @, or &.

For instance, check out this list of some possible object names. Some are okay to use; some are invalid:

today: This is fine
1st: This is bad; it starts with a number
+1: This is bad; it starts with a special character
vars: This is fine
\^_^: This is bad; it starts with a special character
foo: This is fine

Using objects

In the code chunk below, save the results of rnorm(100, mean = 100, sd = 15) to an object named data. Then, on a new line, call the hist() function on data to plot a histogram of the random values.

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Solution

data <- rnorm(100, mean = 100, sd = 15)
hist(data)

What if?

What do you think would happen if you assigned data to a new object named copy, like this? Run the code and then inspect both data and copy.

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Solution

data <- rnorm(100, mean = 100, sd = 15)
copy <- data
data
copy

Good job! R saves a copy of the contents in data to copy.

Datasets

Objects provide an easy way to store datasets in R. In fact, R comes with many toy datasets pre-loaded. Examine the contents of mtcars to see a classic toy dataset. Hint: how could you learn more about the mtcars object?

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Solution

mtcars

Good job! You can learn more about mtcars by examining its help page with ?mtcars.

`rm()`

What if you accidentally overwrite an object? If that object came with R or one of its packages, you can restore the original version of the object by removing your version with rm(). Run rm() on mtcars below to restore the mtcars data set.

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Solution

mtcars <- 1
mtcars
rm(mtcars)
mtcars

Good job! Unfortunately, rm() cannot help you if you overwrite one of your own objects.

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