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Jittered positions: position_jitter

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Jittered positions: position_jitter

Mix.install([
  {:giggly, path: Path.join(__DIR__, "..")},
  {:kino, "~> 0.19"}
  ])

About this notebook

This notebook follows the examples on ggplot2's reference page for position_jitter(), in the order the page gives them. Each example shows ggplot2's code first and then Giggly's. An example Giggly cannot draw yet keeps its ggplot2 code and names what it is waiting for, so the page is also a list of what remains.

position_jitter() adds a little random noise to each position, which can make a small dataset easier to read when at least one of its positions is discrete: points that would sit on top of one another spread apart. The noise goes both ways, by up to 40% of the data's resolution unless width and height say otherwise, and a seed makes it the same every time. Giggly has none of it yet.

Jittered points beside boxplots

# Jittering is useful when you have a discrete position, and a relatively
# small number of points
# take up as much space as a boxplot or a bar
ggplot(mpg, aes(class, hwy)) +
  geom_boxplot(colour = "grey50") +
  geom_jitter()

geom_jitter() is a shortcut for geom_point(position = "jitter").

Not in Giggly yet: geom_jitter(), points placed by position_jitter().

Too much jitter

# If the default jittering is too much, as in this plot:
ggplot(mtcars, aes(am, vs)) +
  geom_jitter()

am and vs are each 0 or 1, so unjittered points would sit on top of one another.

Not in Giggly yet: geom_jitter() and position_jitter().

Less jitter

# You can adjust it in two ways
ggplot(mtcars, aes(am, vs)) +
  geom_jitter(width = 0.1, height = 0.1)
ggplot(mtcars, aes(am, vs)) +
  geom_jitter(position = position_jitter(width = 0.1, height = 0.1))

Not in Giggly yet: geom_jitter() and position_jitter(), with their width and height options.

Reproducible jitter

# Create a jitter object for reproducible jitter:
jitter <- position_jitter(width = 0.1, height = 0.1, seed = 0)
ggplot(mtcars, aes(am, vs)) +
  geom_point(position = jitter) +
  geom_point(position = jitter, color = "red", aes(am + 0.2, vs + 0.2))

With a seed, the position jitters both layers the same way, so each red point sits 0.2 above and to the right of its black one.

Not in Giggly yet: position_jitter() and its seed option, and geom_point()'s position option.

Other notebooks:

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