The `boxplot`

function is the function for creating box plots in base R graphics. You can pass a vector or a data frame (to plot all the columns). Since R 4.0.0 the box plots are gray by default, while in previous versions were white.

```
set.seed(7)
x <- rnorm(200)
boxplot(x)
```

**Horizontal**

The `horizontal`

argument can be set to `TRUE`

to create a horizontal box plot. The default is vertical.

```
set.seed(7)
x <- rnorm(200)
boxplot(x, horizontal = TRUE)
```

**Confidence interval (notch)**

The function also provides the argument `notch`

to add the 95% confidence interval for the median. This is particular interesting for checking if there are evidences that the medians of several box plots differ or not.

```
set.seed(7)
x <- rnorm(200)
boxplot(x, notch = TRUE)
```

**Fill color**

The `col`

argument fills the box with a color. In the following example we are adding a color with transparency making use of the `rgb`

function.

```
set.seed(7)
x <- rnorm(200)
boxplot(x, col = rgb(0, 0.5, 1, alpha = 0.5))
```

**Border color**

You can also change the color of the border of the whole box plot with `border`

.

```
set.seed(7)
x <- rnorm(200)
boxplot(x, col = "white",
border = 4)
```

**Box line type**

The `lty`

argument controls the line type of all the lines of the box plot.

```
set.seed(7)
x <- rnorm(200)
boxplot(x, col = "white",
lty = 2)
```

The function allows customizing each color and each line individually. Most of the arguments below are part of the `bxp`

function, which is called by `boxplot`

.

**Box customization**

```
set.seed(7)
x <- rnorm(200)
boxplot(x,
boxwex = 0.5, # Box width
boxlty = 1, # Box line type
boxlwd = 3, # Box line width
boxcol = 2, # Box border color
boxfill = 4) # Box fill color
```

**Median line customization**

```
set.seed(7)
x <- rnorm(200)
boxplot(x,
medlty = 2, # Line type of the median
medlwd = 2, # Line width of the median
medpch = 21, # pch symbol of the point
medcex = 2, # Size of the point
medcol = 1, # Color of the line
medbg = 4) # Color of the pch (21 to 25)
```

**Whiskers and staple customization**

```
set.seed(7)
x <- rnorm(200)
boxplot(x,
whisklty = 2, # Line type of the whiskers
whisklwd = 2, # Line width of the whiskers
whiskcol = "red", # Color of the whiskers
staplelty = 3, # Line type of the staples
staplelwd = 2, # Line width of the staples
staplecol = "blue") # Color of the staples
```

**Outliers customization**

```
set.seed(7)
x <- rnorm(200)
boxplot(x,
outlty = 0, # Line type
outlwd = 1, # Line width
outpch = 23, # Pch for the outliers
outcex = 2, # Size of the outliers
outcol = 1, # Color
outbg = 4) # bg color (pch 21 to 25)
```

See also