# 7.3 The Analytical Policeman: Visualization for Law and Order

## Quick Question

Create a new line plot, like the one in Video 3, but add the argument “linetype=2”. So the geom_line part of the plotting command should look like:

geom_line(aes(group=1), linetype=2)

What does this do?

Makes the line thicker  close
Changes the color of the line to blue  close
Makes the line dashed  check
Makes the line lighter in color  close

Explanation The linetype parameter makes the line dashed, and the alpha parameter makes the line lighter in color, or more transparent. The two plots can be generated with the following commands: ggplot(WeekdayCounts, aes(x = Var1, y = Freq)) + geom\_line(aes(group=1), linetype=2) + xlab("Day of the Week") + ylab("Total Motor Vehicle Thefts") ggplot(WeekdayCounts, aes(x = Var1, y = Freq)) + geom\_line(aes(group=1), alpha=0.3) + xlab("Day of the Week") + ylab("Total Motor Vehicle Thefts")

Now, change the alpha parameter to 0.3 by replacing “linetype=2” with “alpha=0.3” in the plot command. What does this do?

Makes the line thicker  close
Changes the color of the line to blue  close
Makes the line dashed  close
Makes the line lighter in color  check

Explanation The linetype parameter makes the line dashed, and the alpha parameter makes the line lighter in color, or more transparent. The two plots can be generated with the following commands: ggplot(WeekdayCounts, aes(x = Var1, y = Freq)) + geom\_line(aes(group=1), linetype=2) + xlab("Day of the Week") + ylab("Total Motor Vehicle Thefts") ggplot(WeekdayCounts, aes(x = Var1, y = Freq)) + geom\_line(aes(group=1), alpha=0.3) + xlab("Day of the Week") + ylab("Total Motor Vehicle Thefts")

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