ggplot2: Boxplots with points and fill separation

Question

I have a data which can be divaded via two seperators. One is year and second is a field characteristics.

box<-as.data.frame(1:36)

box$year <- c(1996,1996,1996,1996,1996,1996,1996,1996,1996,
              1997,1997,1997,1997,1997,1997,1997,1997,1997,
              1996,1996,1996,1996,1996,1996,1996,1996,1996,
              1997,1997,1997,1997,1997,1997,1997,1997,1997)
box$year <- as.character(box$year)

box$case <- c(6.40,6.75,6.11,6.33,5.50,5.40,5.83,4.57,5.80,
              6.00,6.11,6.40,7.00,NA,5.44,6.00,  NA,6.00,
              6.00,6.20,6.40,6.64,6.33,6.60,7.14,6.89,7.10,
              6.73,6.27,6.64,6.41,6.42,6.17,6.05,5.89,5.82)

box$code <- c("L","L","L","L","L","L","L","L","L","L","L","L",
              "L","L","L","L","L","L","M","M","M","M","M","M",
              "M","M","M","M","M","M","M","M","M","M","M","M")

colour <- factor(box$code, labels = c("#F8766D", "#00BFC4"))

In boxplots, I want to display points over them, to see how data is distributed. That is easily done with one single boxplot for every year:

ggplot(box, aes(x = year, y = case, fill = "#F8766D")) +
  geom_boxplot(alpha = 0.80) +
  geom_point(colour = colour, size = 5) +
  theme(text = element_text(size = 18),
        axis.title.x = element_blank(),
        axis.title.y = element_blank(),
        panel.grid.minor.x = element_blank(),
        panel.grid.major.x = element_blank(),
        legend.position = "none")

But it become more complicated as I add fill parameter in them:

ggplot(box, aes(x = year, y = case, fill = code)) +
  geom_boxplot(alpha = 0.80) +
  geom_point(colour = colour, size = 5) +
  theme(text = element_text(size = 18),
        axis.title.x = element_blank(),
        axis.title.y = element_blank(),
        panel.grid.minor.x = element_blank(),
        panel.grid.major.x = element_blank(),
        legend.position = "none")

And now the question: How to move these points to boxplot axes, where they belong? As blue points to blue boxplot and red to red one.

[`geom_dotplot`](http://docs.ggplot2.org/current/geom_dotplot.html) using `binaxis = 'y'` may also be of interest. — bouncyball, Jan 20 '17 at 14:00

score 21 · Accepted Answer · answered Jan 20 '17 at 13:54

Like Henrik said, use position_jitterdodge() and shape = 21. You can clean up your code a bit too:

No need to define box, then fill it piece by piece

You can let ggplot hash out the colors if you wish and skip constructing the colors factor. If you want to change the defaults, look into scale_fill_manual and scale_color_manual.

box <- data.frame(year = c(1996,1996,1996,1996,1996,1996,1996,1996,1996,
                  1997,1997,1997,1997,1997,1997,1997,1997,1997,
                  1996,1996,1996,1996,1996,1996,1996,1996,1996,
                  1997,1997,1997,1997,1997,1997,1997,1997,1997),
                  case  = c(6.40,6.75,6.11,6.33,5.50,5.40,5.83,4.57,5.80,
                  6.00,6.11,6.40,7.00,NA,5.44,6.00,  NA,6.00,
                  6.00,6.20,6.40,6.64,6.33,6.60,7.14,6.89,7.10,
                  6.73,6.27,6.64,6.41,6.42,6.17,6.05,5.89,5.82),
                  code = c("L","L","L","L","L","L","L","L","L","L","L","L",
                  "L","L","L","L","L","L","M","M","M","M","M","M",
                  "M","M","M","M","M","M","M","M","M","M","M","M"))

ggplot(box, aes(x = factor(year), y = case, fill = code)) +
  geom_boxplot(alpha = 0.80) +
  geom_point(aes(fill = code), size = 5, shape = 21, position = position_jitterdodge()) +
  theme(text = element_text(size = 18),
        axis.title.x = element_blank(),
        axis.title.y = element_blank(),
        panel.grid.minor.x = element_blank(),
        panel.grid.major.x = element_blank(),
        legend.position = "none")

What is the black point on the left of the lowest circle in 1997? — giordano, Aug 28 '18 at 07:33
If add a group to change the dot shape, it seems not work anymore... — Shixiang Wang, Dec 07 '21 at 03:05

score 6 · Answer 2 · answered Jan 20 '17 at 14:05

6

I see you've already accepted @JakeKaupp's nice answer, but I thought I would throw in a different option, using geom_dotplot. The data you are visualizing is rather small, so why not forego the boxplot?

ggplot(box, aes(x = factor(year), y = case, fill = code))+
    geom_dotplot(binaxis = 'y', stackdir = 'center',
                 position = position_dodge())

answered Jan 20 '17 at 14:05

bouncyball

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Thank you! But my dataset is qutie big, so I have to use boxplots. The set for this question is only a little piece of it. – Kryštof Chytrý Jan 20 '17 at 14:13

ggplot2: Boxplots with points and fill separation

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