### Open Source Your Knowledge, Become a Contributor

Technology knowledge has to be shared and made accessible for free. Join the movement.

## Scatter Plots

A scatter plot graphs the relationships between two numeric variables. It graphs each pair of variables as a point in a two-dimensional space whose coordinates are the corresponding (x, y) values:

# To create a scatter plot with the graphics package,
# call plot with two dataframe columns
plot(faithful$waiting, faithful$eruptions,
main = "Using plot",
xlab = "waiting time (min)",
ylab = "eruption time (min)")
# The arguments pch, col, and cex modify the marker's shape, color, and size
plot(faithful$waiting, faithful$eruptions,
pch = 17,
col = 2,
cex = 1.2,
main = "Specifying pch, col, and cex",
xlab = "waiting times (min)",
ylab = "eruption time (min)")
# Distinguish the points based on the value of another dataframe column
plot(mtcars$hp, mtcars$mpg,
pch = mtcars\$am,
cex = 1.2,
main = "MPG vs. HP by Transmission",
xlab = "horsepower",
ylab = "miles per gallon")
legend("topright", c("automatic", "manual"), pch = c(0, 1))
# Using qplot
qplot(x = waiting,
y = eruptions,
data = faithful,
main = "Using qplot - Waiting Times (sec) vs. Eruptions (min)")
# The graph below shows a scatter plot of car weights vs mpg
qplot(x = wt,
y = mpg,
data = mtcars,
main = "Using qplot - MPG vs. Weight (x1000 lbs)")
# Denoting the number of cylinders by size using the size argument
qplot(x = wt,
y = mpg,
data = mtcars,
size = cyl,
main = "Using qplot with Size - MPG vs. Weight (x1000 lbs) by Cylinder")
# Alternatively, color can be used to encode the number of cylinders
qplot(x = wt,
y = mpg,
data = mtcars,
color = cyl,
main = "Using qplot with Color - MPG vs. Weight (x1000 lbs) by Cylinder")
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Open Source Your Knowledge: become a Contributor and help others learn.  