Visualizing Data

Making a Bar Chart

In tidyverse, there is a function called ggplot which helps us to create charts.

The ggplot function takes in two arguments: data and mapping. We pass an aesthetic or aes() inside mapping. And then inside aes() we add our x and y variables.

Bar Chart

ggplot(mtcars, aes(x = mpg, y = rownames(mtcars))) + geom_bar(stat = "identity")

Exercise

Your turn! Replace x = mpg with x = wt and see what happens.

Bar Chart

ggplot(mtcars, aes(x = , y = rownames(mtcars))) + geom_bar(stat = "identity")

Let’s make it pretty by removing the grid lines, adding a title, changing the color of the bars, reordering the bars, keeping the names in the y axis, and moving the x-axis label to the top.

Bar Chart

ggplot(mtcars, aes(x = mpg, y = rownames(mtcars))) + geom_bar(stat = "identity", fill = "steelblue") + theme_minimal() + theme(axis.title.x = element_blank(), axis.title.y = element_blank(), axis.ticks.y = element_blank(), panel.grid.major.y = element_blank(), panel.grid.minor.y = element_blank(), plot.title.position = "plot") + scale_x_continuous(position = "top", expand = c(0,0)) + labs(title = "Miles per Gallon")

Making a Scatter Plot

Scatter Plot

ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()

Let’s make it pretty by adding a title, a subtitle, changing the color of the points.

Scatter Plot

ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point(color = "steelblue") + labs(title = "Miles per Gallon vs Weight", subtitle = "Efficiency decreases as weight of the car increases") + theme_minimal() + theme(plot.title.position = "plot")

Exercise

Your turn, change the x and y variables to hp and mpg and see what happens.

Scatter Plot

ggplot(mtcars, aes(x = , y = )) + geom_point(color = "steelblue") + labs(title = "Miles per Gallon vs Horsepower", subtitle = "A scatter plot of car horsepower and fuel efficiency") + theme_minimal() + theme(plot.title.position = "plot")

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