# Line types in R: Ultimate Guide For R Baseplot and ggplot

There are six pre-described line types available in base R. You can use those for any type of graphics, like plotting for line charts or developing simple shapes.

In R base plot functions, two options are available **lty** and **lwd**, **lty** stands for line types, and **lwd** for line width. The type of line you can be specified based on a number or a string. In R the default line type is “solid”.

In the case of **ggplot2** package, the parameters **linetype** and **size** are used to decide the type and the size of lines, respectively.

In this tutorial describes how to change line types in R for plots created using either the R base plot or from the ggplot2 package.

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You will understand how to:

- Use the different types line graphs in R.
- Plot two lines and modify the line style for base plots and ggplot
- Adjust the R line thickness by specifying the options lwd and size.
- Change manually the appearance of linetype, color and size

### Different line types in R

From ggpubr package with single line of code we can show the list of line types available in R.

library(ggpubr) show_line_types()

We cam make use below function and write clear labels with number and string.

LineTypes<-function(){ oldPar<-par() par(font=2, mar=c(0,0,0,0)) plot(1, pch="", ylim=c(0,6), xlim=c(0,0.7), axes=FALSE,xlab="", ylab="") for(i in 0:6) lines(c(0.3,0.7), c(i,i), lty=i, lwd=3) text(rep(0.1,6), 0:6, labels=c("0.'blank'", "1.'solid'", "2.'dashed'", "3.'dotted'", "4.'dotdash'", "5.'longdash'", "6.'twodash'")) par(mar=oldPar$mar,font=oldPar$font )} LineTypes()

### Change R base plot line types

R lines functions:-

plot(x, y, type = "l", lty = 1). Create the main plot lines(x, y, type = "l", lty = 1). Add lines onto the plot.

#### Key options:

- x, y: variables to be used for the x and y axes.
- type: display the data as line and/or point. Lowed values: l (display line only), p (show point only), and b (show both).
- pch and cex: setpoints shape and size, respectively.
- lty, lwd: set line types and thickness.
- col: change the color of point and line.
- xlab and ylab: for x and y-axis labels, respectively.

Create some variables for visualization,

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x <- 1:20 y1 <- x*x y2 <- 1*y1

Just plot a first line based on plot function in R,

plot(x, y1, type = "b", frame = FALSE, pch = 19, col = "red", xlab = "x", ylab = "y", lty = 1, lwd = 1)

Now Add a second line

lines(x, y2, pch = 18, col = "blue", type = "b",lty = 2,lwd = 1)

If you want you can add a legend to the plot and set legend lty

legend("topright", legend = c("Line 1", "Line 2"), col = c("red", "blue"),lty = 1:2, cex = 0.8)

## Line Types in ggplot

First, let’s load the data set.

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ToothGrowth$dose <- as.factor(ToothGrowth$dose) head(ToothGrowth)

len supp dose 1 4.2 VC 0.5 2 11.5 VC 0.5 3 7.3 VC 0.5 4 5.8 VC 0.5 5 6.4 VC 0.5 6 10.0 VC 0.5

library(dplyr) df <- ToothGrowth %>% group_by(dose) %>% summarise(len.mean = mean(len)) df

Now created average values based on group by dose.

dose len.mean 1 0.5 10.605 2 1 19.735 3 2 26.100

Let’s plot the same

library(ggplot2) ggplot(data = df, aes(x = dose, y = len.mean, group = 1)) + geom_line(linetype = "dashed")+ geom_point()

Create a line plot for multiple groups

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library(dplyr)

df2 <- ToothGrowth %>%

group_by(dose, supp) %>%

summarise(len.mean = mean(len))

df2

dose supp len.mean 1 0.5 OJ 13.23 2 0.5 VC 7.98 3 1 OJ 22.70 4 1 VC 16.77 5 2 OJ 26.06 6 2 VC 26.14

ggplot(df2, aes(x = dose, y = len.mean, group = supp)) + geom_line(aes(linetype = supp, color = supp))+ geom_point(aes(color = supp))+theme_bw()

Now change line type and color manually

ggplot(df2, aes(x = dose, y = len.mean, group = supp)) + geom_line(aes(linetype = supp, color = supp))+ geom_point(aes(color = supp))+theme_bw()+ scale_linetype_manual(values=c("solid", "longdash"))+ scale_color_manual(values=c("#00AFBB","#FC4E07"))

## Conclusion

Use **lty** and **lwd** options, for changing lines type and thickness in R base graphics and in ggplot **linetype** and **size** are used.

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