Annotate text on plot
The plot that has been created using the ggplot2 method can also be annotated with various text items and their corresponding positions can be specified. For example, the text point at any respective coordinates of the x-cord and y-cord can be used to be labeled by a specific text value in the following code snippet the data point at the location 5,2 is labeled with the name “PT1”. The annotate method has the following syntax.
Syntax : annotate(text, x=,y=,label=)
Arguments:
x-the x coordinate where the x is annotated
y-the y coordinate of the annotated text
label-the label to be assigned at these coordinates
R
#creating the plot #assigning groups based on col2 values ggplot (data_frame, aes (col1, col3, colour=col2)) + geom_point () + annotate ( "text" , x = 5, y = 2, label = "pt1" ) |
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