how to have 4 distinct stems in a lollipop plot

I have the following dataframe df_long:

set.seed(123) # For reproducibility
df_long <- data.frame(
 trait = rep(c("Trait1", "Trait2", "Trait3", "Trait4", "Trait5"), each = 4), 
 type = rep(c("eur_ita", "eur_ita_2", "eur_ita_3", "eur_ita_4"), times = 5),   
 value = c(runif(5, 5, 15), runif(5, 8, 20), runif(5, 1, 12), runif(5, 4, 18)),
 macro_cat3 = rep(c("Category1", "Category2"), each = 10) # Dividing into two macro categories
)

and I wrote the following code to make a lollipop plot:

ggplot(df_long, aes(x = trait, y = value, color = type, shape = type, alpha = type)) +
  # Add the lollipop stems
  geom_segment(
    aes(x = trait, xend = trait, y = 0, yend = value),
    position = position_dodge(width = 0.8), # Dodge stems horizontally
    linewidth = 0.6 # Adjust stem thickness
  ) +
  # Add the lollipop heads
  geom_point(
    position = position_dodge(width = 0.8), # Dodge points horizontally
    size = 3 # Adjust point size
  ) +
  facet_wrap(~ macro_cat3, scales = "free_x", ncol = 4) +
  labs(x = "Trait", y = "Percentage of r2", color = "Type", shape = "Type", alpha = "PRS Type") +
  scale_color_manual(
    values = c(
      "eur_ita" = "red",
      "eur_ita_2" = "black",
      "eur_ita_3" = "green",
      "eur_ita_4" = "gray"
    )
  ) +
  scale_alpha_manual(
    values = c(
      "eur_ita" = 1,
      "eur_ita_2" = 0.9,
      "eur_ita_3" = 0.9,
      "eur_ita_4" = 1
    ),
    guide = "none"
  ) +
  scale_shape_manual(
    values = c(
      "eur_ita" = 18,
      "eur_ita_2" = 18,
      "eur_ita_3" = 19,
      "eur_ita_4" = 19
    )
  ) +
  theme_minimal() +
  theme(
    axis.text.x = element_text(angle = 45, hjust = 1, size = 10),
    strip.text = element_text(size = 12),
    legend.position = "bottom",
    panel.border = element_rect(color = "black", fill = NA, linewidth = 0.8),
    strip.background = element_blank()
  )

and I got the attached image as an example.

How can I have a vertical stem per each dot, so as to have 4 lollipops per each x value?

Solution

Rather than using geom_segment, use geom_linerange For example

  geom_linerange(
    aes(x = trait, ymin = 0, ymax = value),
    position = position_dodge(width = 0.8), # Dodge stems horizontally
    linewidth = 0.6 # Adjust stem thickness
  )

Will produce