Line chart

We can create a line chart in R by using the following code:

plot(x, y, type = '', col = '', main = 'title', xlab = 'x-axis', ylab = 'y-axis')

Here x is the vector with the x-axis coordinates and y is the vector with the y-axis coordinates. You can also specify the line char type in the type= arugment by writing:

• “p”: Draw only the points
• “l”: Draw only the lines
• “o”: Draw both points and lines

As an example, we will be plotting \(y=2x\):

x <- c(-2,-1,0,1,2)
y <- c(-4,-2,0,2,4)

plot(x, y, type = 'o', col = 'blue', main = 'y=2x', xlab = 'x', ylab = 'y')

Adding lines

We can also add a horizontal line in the line chart by using the following code:

abline(h = y)

where y is the coordinate that you would like to have. Alternatively, you can add a vertical line to the line chart by using the following code:

abline(v = x)

where x is the x-coordinate. Inside the abline() function, you can set the lty argument, which allows you to change the line type (you can have dashed lines, etc). The list of line types can be found on this website:

• http://www.sthda.com/english/wiki/line-types-in-r-lty

As usual, you can also change the color of the line by putting col= argument inside.

x <- c(-2,-1,0,1,2)
y <- c(-4,-2,0,2,4)

plot(x, y, type = 'o', col = 'blue', main = 'y=2x', xlab = 'x', ylab = 'y')

# The red line comes from this code
abline(h=0, lty=1, col='red')

# The black line comes from this code
abline(v=0, lty=2, col='black')

©2021 by Daiki Tagami. All rights reserved.