R Plot

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)

Output:


To draw more points, use vectors:

Example

Draw two points in the diagram, one at position (1, 3) and one in position (4, 5):
plot(c(1, 4), c(3, 5)

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))


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)

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)


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")


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")

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")

Size

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

Example:
plot(1:10, cex=2)

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)


Sample Program 
plot(1:10,col='red',pch=2,cex=2)

Output:


Plot Trigonometric Function in R

In R, we can also plot trigonometric functions.Let's generate a sine wave plot,

# sequence vector of values from -pi to pi with 0.1 interval
x = seq(-pi,pi,0.1)
# respective sine value of x
y = sin(x)
# plot y against x
plot(x,y,col='red',type="l")

Output:


In the above example, we have generated a sine wave plot.We have used the seq() function to create the sequence vector x of values from -pi to pi with 0.1 interval. And assigned respective sine values of x to y.Finally, we plotted y against x using plot().

Note: Similarly, we can generate wave plots of other trigonometric functions.

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