inst/examples/ex-simplicial-complex.R

In rrrlw/ggtda: 'ggplot2' Extension to Visualize Topological Persistence

set.seed(1)
s <- seq(0, 2*pi, length.out = 40)
df <- data.frame(
  x = cos(s) + rnorm(40, 0, .1),
  y = sin(s) + rnorm(40, 0, .1)
)

# default
ggplot(df, aes(x, y)) +
  coord_fixed() +
  geom_simplicial_complex(radius = .4)
# higher-dimensional simplices are not more opaque but cause overlap
ggplot(df, aes(x, y)) +
  coord_fixed() +
  geom_simplicial_complex(radius = .4, dimension_max = 3L)

# visualizing dimension w/ face & alpha:
ggplot(df, aes(x, y)) +
  coord_fixed() +
  geom_simplicial_complex(
    mapping = aes(alpha = after_stat(face)),
    radius = .3, dimension_max = 4L
  ) +
  scale_alpha_ordinal(range = c(.1, .6))
# visualizing dimension w/ dimension & fill:
ggplot(df, aes(x, y)) +
  coord_fixed() +
  geom_simplicial_complex(
    mapping = aes(fill = after_stat(dimension)),
    radius = .3, dimension_max = 4L, alpha = .25
  ) +
  scale_fill_continuous(type = "viridis")

# with a zero radius or diameter
ggplot(df, aes(x = x, y = y)) +
  coord_fixed() +
  stat_simplicial_complex(radius = 0)
# with a too-small radius or diameter
ggplot(df, aes(x = x, y = y)) +
  coord_fixed() +
  stat_simplicial_complex(radius = 0.01)

# Visualizing multiple groups together
s <- c(s, s)
df_mix <- data.frame(
  x = cos(s) + rnorm(80, 0, .1),
  y = sin(s) + rnorm(80, 0, .1)
)
df_mix$x <- df_mix$x + rep(c(-2, 2), length.out = 80)
df_mix$lab <- rep(c("a", "b"), length.out = 80)

ggplot(df_mix, aes(x, y, fill = lab)) +
  geom_simplicial_complex(radius = .4)