# Accessing Built-in Datasets in R

R comes with many built-in datasets which are quite useful while learning R. To begin learning the basics of data visualization in R, we will make use of some of these datasets.

### Datasets in the 'datasets' package

Many datasets are included in a package called datasets which is distributed with R so these datasets are instantly available to you for use. For example, two datasets namely cars and pressure are included in this default datasets package. So, you can access their data by using functions such as head(cars)summary(cars), etc.

The following examples show results of calls to these functions:

> head(cars)
speed dist
1     4    2
2     4   10
3     7    4
4     7   22
5     8   16
6     9   10
>

> summary(cars)
speed           dist
Min.   : 4.0   Min.   :  2.00
1st Qu.:12.0   1st Qu.: 26.00
Median :15.0   Median : 36.00
Mean   :15.4   Mean   : 42.98
3rd Qu.:19.0   3rd Qu.: 56.00
Max.   :25.0   Max.   :120.00
>

> head(pressure)
temperature pressure
1           0   0.0002
2          20   0.0012
3          40   0.0060
4          60   0.0300
5          80   0.0900
6         100   0.2700
>

> summary(pressure)
temperature     pressure
Min.   :  0   Min.   :  0.0002
1st Qu.: 90   1st Qu.:  0.1800
Median :180   Median :  8.8000
Mean   :180   Mean   :124.3367
3rd Qu.:270   3rd Qu.:126.5000
Max.   :360   Max.   :806.0000
>


To learn more about a dataset, you can use the help function as help(cars).

If you want to get a list of all the datasets, you can do so using the data() function.

### Datasets in Other Packages

Any R package can choose to include datasets. You can access the data from a package using thedata() function by using the package argument as follows:

data(datasetname, package="packagename")


For example, there's a popular package called MASS which contains datasets (such as Cars93). We can access the Cars93 dataset by calling the data() function.

> data(Cars93, package="MASS")


After this call to data(), the Cars93 dataset is available for use in R.