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:

1. We use the data set “mtcars”.
2. 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:

1. We are using the required parameters to plot the graph.
2. 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:

Scatter plots in R Language

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:

Scatter plots in R Language

Scatterplot with fitted values

In order to create R Scatterplot Chart:

1. We are using the ggplot2 package provides ggplot() and geom_point() function for creating a scatterplot.
2. 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:

Scatter plots in R Language

To create R Scatterplot Chart, Add a sub-title:

1. We use the additional function, In ggplot we add the data set “mtcars” with this adding ‘aes’, ‘geom_point’.
2. 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:

Scatter plots in R Language

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:

Scatter plots in R Language

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