Annotating the Graph with the plotted area
The graph can also be plotted with a rectangular area or a square area depending on the x-coordinates starting and ending as well as y-coordinates starting and ending. In order to construct a rectangle or a square over that area. Depending upon the respective area that is enclosed within it. The same annotate method can be used with the first parameter specifying “rect” instead of text. In order to plot a rectangle, we can use the following syntax
Syntax : annotate(“rect”, xmin, xmax, ymin, ymax, alpha)
Arguments:
xmin-the starting x coordinate
xmax-the ending x coordinate
ymin-the starting y coordinate
ymax-the ending y coordinate
In the following code snippet, a rectangle is plotted starting from the x coordinates to till the value of 7 and y coordinates between 1.5 to 4.5 respectively.
R
#creating the plot #assigning groups based on col2 values #highlighting the rectangular based area ggplot (data_frame, aes (col1, col3, colour=col2)) + geom_point () + annotate ( "rect" , xmin = 2, xmax = 7, ymin = 1.5, ymax = 4.5, alpha = .5) |
Output
Working with Axes in R using ggplot2
The ggplot2 package is a powerful and widely used package for graphic visualization. It can be used to provide a lot of aesthetic mappings to the plotted graphs. This package is widely available in the R Programming Language. The package can be downloaded and installed into the working space using the following command.
install.packages("ggplot2")
The ggplot method can be used to create a ggplot object. The graphical object is used to create plots by providing the data and its respective points. The data can be plotted using both points as well as lines.
Syntax : ggplot(data, aes = )
Arguments :
data – The data to be plotted
aes – The aesthetic mappings
The geom_point method can be used to plot the data points on the existing visualization that has been created. The color has been assigned based on the grouping values assigned in the col2 of the data plane in the following code snippet.
That is since there are three groups a, b, and c three different colors are used to denote the values contained in these three groups. These parameters are specified in the aesthetic mappings, as discussed above in the ggplot method.
R
#installing the required libraries library ( "ggplot2" ) #creating a data frame data_frame = data.frame (col1 = c (1,4,2,5,6,9,5,3,6,3), col2 = c ( "a" , "b" , "a" , "c" , "b" , "b" , "b" , "a" , "c" , "a" ), col3 = c (3,2,4,2,1,4,8,6,4,2)) #creating the plot #assigning groups based on col2 values ggplot (data_frame, aes (col1, col3, colour=col2)) + geom_point () |
Output