The **iris** dataset is a built-in dataset in R that contains measurements on 4 different attributes (in centimeters) for 50 flowers from 3 different species.

This tutorial explains how to explore and summarize a dataset in R, using the iris dataset as an example.

**Related:** A Complete Guide to the mtcars Dataset in R

**Load the Iris Dataset**

Since the iris dataset is a built-in dataset in R, we can load it by using the following command:

**data(iris)**

We can take a look at the first six rows of the dataset by using the **head()** function:

**#view first six rows of iris dataset
head(iris)
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1 5.1 3.5 1.4 0.2 setosa
2 4.9 3.0 1.4 0.2 setosa
3 4.7 3.2 1.3 0.2 setosa
4 4.6 3.1 1.5 0.2 setosa
5 5.0 3.6 1.4 0.2 setosa
6 5.4 3.9 1.7 0.4 setosa
**

**Summarize the Iris Dataset**

We can use the **summary()** function to quickly summarize each variable in the dataset:

**#summarize iris dataset
summary(iris)
Sepal.Length Sepal.Width Petal.Length Petal.Width
Min. :4.300 Min. :2.000 Min. :1.000 Min. :0.100
1st Qu.:5.100 1st Qu.:2.800 1st Qu.:1.600 1st Qu.:0.300
Median :5.800 Median :3.000 Median :4.350 Median :1.300
Mean :5.843 Mean :3.057 Mean :3.758 Mean :1.199
3rd Qu.:6.400 3rd Qu.:3.300 3rd Qu.:5.100 3rd Qu.:1.800
Max. :7.900 Max. :4.400 Max. :6.900 Max. :2.500
Species
setosa :50
versicolor:50
virginica :50 **

For each of the numeric variables we can see the following information:

**Min**: The minimum value.**1st Qu**: The value of the first quartile (25th percentile).**Median**: The median value.**Mean**: The mean value.**3rd Qu**: The value of the third quartile (75th percentile).**Max**: The maximum value.

For the only categorical variable in the dataset (Species) we see a frequency count of each value:

**setosa**: This species occurs 50 times.**versicolor**: This species occurs 50 times.**virginica**: This species occurs 50 times.

We can use the **dim()** function to get the dimensions of the dataset in terms of number of rows and number of columns:

**#display rows and columns
dim(iris)
[1] 150 5
**

We can see that the dataset has **150** rows and **5** columns.

We can also use the **names()** function to display the column names of the data frame:

**#display column names
names(iris)
[1] "Sepal.Length" "Sepal.Width" "Petal.Length" "Petal.Width" "Species"
**

**Visualize the Iris Dataset**

We can also create some plots to visualize the values in the dataset.

For example, we can use the **hist()** function to create a histogram of the values for a certain variable:

**#create histogram of values for sepal length
hist(iris$Sepal.Length,
col='steelblue',
main='Histogram',
xlab='Length',
ylab='Frequency')
**

We can also use the **plot()** function to create a scatterplot of any pairwise combination of variables:

**#create scatterplot of sepal width vs. sepal length
plot(iris$Sepal.Width, iris$Sepal.Length,
col='steelblue',
main='Scatterplot',
xlab='Sepal Width',
ylab='Sepal Length',
pch=19)**

We can also use the **boxplot()** function to create a boxplot by group:

**#create scatterplot of sepal width vs. sepal length
boxplot(Sepal.Length~Species,
data=iris,
main='Sepal Length by Species',
xlab='Species',
ylab='Sepal Length',
col='steelblue',
border='black')**

The x-axis displays the three species and the y-axis displays the distribution of values for sepal length for each species.

This type of plot allows us to quickly see that the sepal length tends to be largest for the virginica species and smallest for the setosa species.

**Additional Resources**

The following tutorials further explain how to summarize datasets in R:

The Easiest Way to Create Summary Tables in R

How to Calculate Five Number Summary in R

Thank you so much Zach! The contents of this site are rich and super duper easy to understand.

ok

Hi! How would I work out the strength of association between Species and Sepal.Length using the lm() function? Thank you.