R Plotting

Plot

The plot() function is used to draw points (markers) in a diagram.

The function takes parameters for specifying points in the diagram.

Parameter 1 specifies points on the x-axis.

Parameter 2 specifies points on the y-axis.

At its simplest, you can use the plot() function to plot two numbers against each other:

Example

Draw one point in the diagram, at position (1) and position (3):

plot(1, 3)

Result:

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To draw more points, use vectors:

Example

Draw two points in the diagram, one at position (1, 3) and one in position (8, 10):

plot(c(1, 8), c(3, 10))

Result:

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Multiple Points

You can plot as many points as you like, just make sure you have the same number of points in both axis:

Example

plot(c(1, 2, 3, 4, 5), c(3, 7, 8, 9, 12))

Result:

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For better organization, when you have many values, it is better to use variables:

Example

x <- c(1, 2, 3, 4, 5)
y <- c(3, 7, 8, 9, 12)

plot(x, y)

Result:

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Sequences of Points

If you want to draw dots in a sequence, on both the x-axis and the y-axis, use the : operator:

Example

plot(1:10)

Result:

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Draw a Line

The plot() function also takes a type parameter with the value l to draw a line to connect all the points in the diagram:

Example

plot(1:10, type="l")

Result:

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Plot Labels

The plot() function also accept other parameters, such as main, xlab and ylab if you want to customize the graph with a main title and different labels for the x and y-axis:

Example

plot(1:10, main="My Graph", xlab="The x-axis", ylab="The y axis")

Result:

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Graph Appearance

There are many other parameters you can use to change the appearance of the points.

Colors

Use col="color" to add a color to the points:

Example

plot(1:10, col="red")

Result:

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Size

Use cex=number to change the size of the points (1 is default, while 0.5 means 50% smaller, and 2 means 100% larger):

Example

plot(1:10, cex=2)

Result:

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Point Shape

Use pch with a value from 0 to 25 to change the point shape format:

Example

plot(1:10, pch=25, cex=2)

Result:

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The values of the pch parameter ranges from 0 to 25, which means that we can choose up to 26 different types of point shapes: