rggplot2legendgeom

Hide certain legend items by axis in geom_parallel_set plot

I would like to hide certain parts of the legend of the plot below by axis. In other words, suppress legend items for either the "Class", "Sex", "Age", and "Survived".

Example parallel sets: 1

library(ggforce)

data <- reshape2::melt(Titanic)
data <- gather_set_data(data, 1:4)
ggplot(data, aes(x, id = id, split = y, value = value)) +
  geom_parallel_sets(aes(fill = Class), alpha = 0.3, axis.width = 0.1) +
  geom_parallel_sets_axes(aes(fill=y), axis.width = 0.1) +
  geom_parallel_sets_labels(colour = 'white') +
  scale_x_discrete(limits = c("Class", "Sex", "Age", "Survived"), expand = c(0, 0)) +
  theme(
    panel.background = element_blank(),
    axis.ticks.y = element_blank(),
    axis.text.y = element_blank(),
    axis.title.x = element_blank()
  )

I have researched the documentation examples without success.

Solution

  • Based on your comment, to omit certain legend items without affecting the plot, you could use scale_fill_manual with guide = guide_legend(...) to suppress the relevant legend keys and labels. Note that because your variables are factors, as.character() is needed to return the text values.

    First, create hex colour and label vectors:

    library(ggforce)

# Return vector of legend values
unique_vars <- unique(unlist(data[,c("Class", "Sex", "Age", "Survived")]))

# Create vector of hex colour values for all legend items with
# colours to match default ggplot2 colours (as in your example plot)
legend_col <- scales::hue_pal()(length(unique_vars))

    Omit "No" and "Yes":

    ggplot(data, aes(x, id = id, split = y, value = value)) +
  geom_parallel_sets(aes(fill = Class), alpha = 0.3, axis.width = 0.1) +
  geom_parallel_sets_axes(aes(fill = y), axis.width = 0.1) +
  geom_parallel_sets_labels(colour = 'white') +
  scale_x_discrete(limits = c("Class", "Sex", "Age", "Survived"), expand = c(0, 0)) +
  scale_fill_manual(
    name = "Variables",
    values = legend_col,
    labels = c(as.character(unique_vars[1:8]), "", ""),
    guide = guide_legend(override.aes = list(fill = c(legend_col[1:8], NA, NA)))
  ) +
  theme(
    legend.key = element_rect(fill = NA, colour = NA),
    panel.background = element_blank(),
    axis.ticks.y = element_blank(),
    axis.text.y = element_blank(),
    axis.title.x = element_blank()
  )

    1

    Omit "Child" and "Adult":

    ggplot(data, aes(x, id = id, split = y, value = value)) +
  geom_parallel_sets(aes(fill = Class), alpha = 0.3, axis.width = 0.1) +
  geom_parallel_sets_axes(aes(fill = y), axis.width = 0.1) +
  geom_parallel_sets_labels(colour = 'white') +
  scale_x_discrete(limits = c("Class", "Sex", "Age", "Survived"), expand = c(0, 0)) +
  scale_fill_manual(
    name = "Variables",
    values = legend_col,
    labels = c(as.character(unique_vars[c(1:6, 9:10)]), "", ""),
    guide = guide_legend(override.aes = list(fill = c(legend_col[c(1:6, 9:10)], NA, NA)))
  ) +
  theme(
    legend.key = element_rect(fill = NA, colour = NA),
    panel.background = element_blank(),
    axis.ticks.y = element_blank(),
    axis.text.y = element_blank(),
    axis.title.x = element_blank()
  )

    2