grid_jittering

library(tidyverse)

example_df <- tribble(
  ~Year, ~Category, ~Name,
  2015,  "A",       "1",
  2015,  "A",       "3",
  2015,  "A",       "5",
  2015,  "C",       "2",
  2015,  "C",       "4",
  2016,  "A",       "1",
  2016,  "A",       "4",
  2016,  "B",       "2",
  2016,  "B",       "3",
  2016,  "B",       "5",
  2017,  "B",       "1",
  2017,  "B",       "2",
  2017,  "B",       "3",
  2017,  "B",       "4",
  2017,  "C",       "5",
  2018,  "B",       "1",
  2018,  "B",       "2",
  2018,  "B",       "3",
  2018,  "B",       "4",
  2018,  "B",       "5"
) %>% 
  mutate(Year = factor(Year))

max_group = example_df %>% 
  count(Year, Category) %>%
  pull(n) %>%
  max

grid_width  = ceiling(max_group^0.5)
grid_height = ceiling(max_group / grid_width)

example_df_grid <- example_df %>%
  group_by(Year, Category) %>%
  arrange(Name) %>%
  mutate(nudge_x = ((row_number() - 1) %% grid_width / (grid_width - 1)) * 0.2,
         nudge_y = -((row_number() - 1) %/% grid_width) / grid_height * 0.3) %>%
  ungroup()


ggplot(example_df_grid, 
       aes(x = Year, 
           y = fct_rev(Category), 
           color = Name)) +
  geom_point(size = 3, 
             position = position_nudge(x = example_df_grid$nudge_x,
                                       y = example_df_grid$nudge_y)) +
  labs(title = "No jittering; overplotting") +
  theme(legend.position = "bottom")