Basics
The basic structure of a plot command looks like this:
ggplot(data = {dataset name}) + {geom_function}(mapping = aes(<mappings>))
Make it fancy:
Here's an example where we set the color to a variable:
ggplot(data = Over18) + geom_point(mapping = aes (x=MARHYP, y=AGEP, color=SEX))
Here's another example if we just want the whole plot to be a certain color (not set to a variable, just to make it pretty!):
ggplot(data = {datasetname}) + {geom_function}(mapping = aes (x=BLAH, y=NAH), color = "blue")
Some geoms to get you started:
geom_point Makes a scatterplot. Add "jitter" to make each point more noticeable if there are many overlapping points. Example:
ggplot(data=adultfemales) + geom_point(mapping=aes(x=MARHYP, y=AGEP), position = "jitter", color = "green")
geom_bar Counts the number of times something is listed in your dataset and displays the counts in bars. If you want to set a y axis variable other than the count (if the count is already present in the data), you need to add stat="identity"
like this:
ggplot(data = TopDogs) + geom_bar (mapping = aes (x=DogName, y = Count), stat = "identity")
geom_smooth Makes a smoothed line fitted to the data (does not hit all points of data).
Find more geoms on the ggplot2 Cheat Sheet here: RStudio ggplot Cheat Sheet
Hint: You can always type ??{geom_name} to learn how a specific geom works and see examples of it.