ggplot2 Geoms

Introduction

Geoms are the visual elements (points, lines, bars) in ggplot2. Different geoms create different plot types.

Point Geom

ggplot(df, aes(x = var1, y = var2)) +
  geom_point()

# With options
ggplot(df, aes(x = var1, y = var2)) +
  geom_point(shape = 21, 
             fill = "blue",
             size = 3,
             alpha = 0.7)

Line Geom

# Line plot
ggplot(df, aes(x = x, y = y)) +
  geom_line()

# Point and line
ggplot(df, aes(x = x, y = y)) +
  geom_point() +
  geom_line()

Bar Geoms

# Bar plot
ggplot(df, aes(x = category, y = value)) +
  geom_bar(stat = "identity")

# Stacked bar
ggplot(df, aes(x = category, y = value, fill = type)) +
  geom_bar(stat = "identity")

# Horizontal bar
ggplot(df, aes(x = value, y = category)) +
  geom_bar(stat = "identity") +
  coord_flip()

Summary Geoms

# Box plot
ggplot(df, aes(x = category, y = value)) +
  geom_boxplot()

# Violin plot
ggplot(df, aes(x = category, y = value)) +
  geom_violin()

# Error bars
ggplot(df, aes(x = x, y = y)) +
  geom_point() +
  geom_errorbar(aes(ymin = lower, ymax = upper))

Summary

Choose appropriate geoms for your data and visualization goals. Combine geoms for complex plots.