Scatter plots in R Language
A scatter plot is a set of dotted points representing individual data pieces on the horizontal and vertical axis. In a graph in which the values of two variables are plotted along the X-axis and Y-axis, the pattern of the resulting points reveals a correlation between them.
R – Scatter plots
We can create a scatter plot in R Programming Language using the plot() function.
Syntax: plot(x, y, main, xlab, ylab, xlim, ylim, axes)
Parameters:
- x: This parameter sets the horizontal coordinates.
- y: This parameter sets the vertical coordinates.
- xlab: This parameter is the label for horizontal axis.
- ylab: This parameter is the label for vertical axis.
- main: This parameter main is the title of the chart.
- xlim: This parameter is used for plotting values of x.
- ylim: This parameter is used for plotting values of y.
- axes: This parameter indicates whether both axes should be drawn on the plot.
Simple Scatterplot Chart
In order to create Scatterplot Chart:
- We use the data set “mtcars”.
- Use the columns “wt” and “mpg” in mtcars.
Example:
R
input <- mtcars[, c ( 'wt' , 'mpg' )] print ( head (input)) |
Output:
Creating a Scatterplot Graph
In order to create an R Scatterplot graph:
- We are using the required parameters to plot the graph.
- In this ‘xlab’ describes the X-axis and ‘ylab’ describes the Y-axis.
Example:
R
# Get the input values. input <- mtcars[, c ( 'wt' , 'mpg' )] # Plot the chart for cars with # weight between 1.5 to 4 and # mileage between 10 and 25. plot (x = input$wt, y = input$mpg, xlab = "Weight" , ylab = "Milage" , xlim = c (1.5, 4), ylim = c (10, 25), main = "Weight vs Milage" ) |
Output:
Scatterplot Matrices
When we have two or more variables and we want to correlate between one variable and others so we use a R scatterplot matrix.
pairs() function is used to createR matrices of scatterplots.
Syntax: pairs(formula, data)
Parameters:
- formula: This parameter represents the series of variables used in pairs.
- data: This parameter represents the data set from which the variables will be taken.
Example:
R
# Plot the matrices between # 4 variables giving 12 plots. # One variable with 3 others # and total 4 variables. pairs (~wt + mpg + disp + cyl, data = mtcars, main = "Scatterplot Matrix" ) |
Output:
Scatterplot with fitted values
In order to create R Scatterplot Chart:
- We are using the ggplot2 package provides ggplot() and geom_point() function for creating a scatterplot.
- Also we are using the columns “wt” and “mpg” in mtcars.
Example:
R
# Loading ggplot2 package library (ggplot2) # Creating scatterplot with fitted values. # An additional function stst_smooth # is used for linear regression. ggplot (mtcars, aes (x = log (mpg), y = log (drat))) + geom_point ( aes (color = factor (gear))) + stat_smooth (method = "lm" , col = "#C42126" , se = FALSE , size = 1 ) |
Output:
Adding title with dynamic name
To create R Scatterplot Chart, Add a sub-title:
- We use the additional function, In ggplot we add the data set “mtcars” with this adding ‘aes’, ‘geom_point’.
- Use the Title, Caption, Subtitle.
Example:
R
# Loading ggplot2 package library (ggplot2) # Creating scatterplot with fitted values. # An additional function stst_smooth # is used for linear regression. new_graph<- ggplot (mtcars, aes (x = log (mpg), y = log (drat))) + geom_point ( aes (color = factor (gear))) + stat_smooth (method = "lm" , col = "#C42126" , se = FALSE , size = 1) # in above example lm is used for linear regression # and se stands for standard error. # Adding title with dynamic name new_graph + labs ( title = "Relation between Mile per hours and drat" , subtitle = "Relationship break down by gear class" , caption = "Authors own computation" ) |
Output:
3D Scatterplots
Here we will use R scatterplot3D package to create 3D scatterplots, this package can plot R scatterplots in 3D using scatterplot3d() methods.
R
# 3D Scatterplot library (plotly) attach (mtcars) plot_ly (data=mtcars,x=~mpg,y=~hp,z=~cyl,color=~gear) |
Output: