11.4 Bar Chart Basic
%>% ds ggplot(aes(x=wind_dir_3pm)) + geom_bar() + scale_y_continuous(labels=comma) + labs(x=vnames["wind_dir_3pm"], y="Count")
A common and simple plot is the bar chart which displays
bars with a height that corresponds to the number of observations
having that value of the variable displayed on the x-axis. We use
ggplot2::geom_bar() to add a bar chart layer to a plot. Only
an x-axis aesthetic is required using ggplot2::aes() with the
x= option. The y-axis is automatically computed.
In our example we pipe the dataset on to ggplot2::ggplot(),
specifying the x-axis as the categoric variable
wind_dir_3pm (the x-axis). The count is automatically
determined from the dataset by ggplot2::geom_bar() which then
adds the layer of bars to the plot.
The y-ticks use commas with the ggplot2::scale_continuous()
function using the
labels=``comma option. It is crucial that
for large numbers commas separate the thousands, so that the reader is
able to easily read the number. There can be catastrophic outcomes
from a misreading of numbers.
The x-axis and y-axis labels are set using ggplot2::labs()
y= options. The x-label uses the
original dataset’s variable name as recorded in the template variable
WindDir3pm). The y-label is set to be
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