Tables of a persistent homology result

Usage

# S3 method for class 'persistent_homology'
hg_get(
  x,
  what = c("persistence", "betti"),
  ...,
  dimension = NULL,
  sort_by = NULL,
  top = NULL
)

Arguments

x: A persistent_homology object from hg_homology().
what: "persistence" (default) for the persistence diagram, or "betti" for the Betti curves across the filtration.
...: Additional arguments (ignored).
dimension: Integer or NULL. Keep only this homological dimension.
sort_by: NULL (construction order, default) or "persistence" - longest-lived features first. Only for what = "persistence".
top: Integer or NULL. Return only the first top rows, applied after any filter and after sort_by, so sort_by and top compose. Default NULL returns every row.

Value

A data.frame. For what = "persistence", one row per feature: dimension, birth, death, persistence. For what = "betti", one row per (threshold, dimension): threshold, dimension, betti.

Examples

set.seed(1)
w <- matrix(runif(36), 6, 6, dimnames = list(letters[1:6], letters[1:6]))
w <- (w + t(w)) / 2
diag(w) <- 0
ph <- hg_homology(w, n_steps = 10)
hg_get(ph, sort_by = "persistence")
#>    dimension     birth     death persistence
#> 1          0 0.7427237 0.0000000  0.74272370
#> 2          3 0.2344513 0.0000000  0.23445130
#> 3          3 0.2344513 0.0000000  0.23445130
#> 4          0 0.7427237 0.5838612  0.15886254
#> 5          3 0.1558863 0.0000000  0.15588635
#> 6          3 0.1558863 0.0000000  0.15588635
#> 7          3 0.1558863 0.0000000  0.15588635
#> 8          1 0.5170309 0.3655044  0.15152644
#> 9          0 0.7427237 0.6583996  0.08432412
#> 10         0 0.7427237 0.6902349  0.05248880
#> 11         0 0.7427237 0.7162022  0.02652146
#> 12         1 0.6441215 0.6299381  0.01418338
hg_get(ph, what = "betti", dimension = 0)
#>      threshold dimension betti
#> 1  0.742723701         0     5
#> 2  0.661024094         0     3
#> 3  0.579324487         0     1
#> 4  0.497624880         0     1
#> 5  0.415925273         0     1
#> 6  0.334225665         0     1
#> 7  0.252526058         0     1
#> 8  0.170826451         0     1
#> 9  0.089126844         0     1
#> 10 0.007427237         0     1