Read Per-Element Monoid Measures

Applies the named monoid's measure() function to each leaf entry in sequence order, returning the results as a new flexseq.

Usage

get_measures(x, monoid_name)

Arguments

x

A flexseq (or any immutables subclass).

monoid_name

Name of an attached monoid.

Value

A plain unnamed flexseq of length length(x). Entry i is the monoid's measure() applied to the i-th leaf entry.

Details

Each leaf in a finger tree stores a structure-specific entry (flexseq: the raw element; ordered_sequence: list(value, key); priority_queue: list(value, priority); interval_index: list(value, start, end)). A monoid's measure() function is defined over that entry shape, and this accessor exposes the per-element values that would be combined to produce the cached aggregate.

Returns a flexseq rather than a base list so results can be piped back into other immutables operations; use as.list() or unlist() to convert.

See also

get_measure(), measure_monoid(), fapply()

Examples

sum_m <- measure_monoid(`+`, 0, function(el) el)
x <- add_monoids(as_flexseq(c(3, 1, 4, 1, 5, 9)), list(sum = sum_m))
get_measures(x, "sum") |> unlist()
#> [1] 3 1 4 1 5 9

q <- priority_queue("a", "b", "c", priorities = c(5, 1, 3))
# Per-element .pq_min measures — each is list(has, priority).
get_measures(q, ".pq_min")
#> Unnamed flexseq with 3 elements.
#> 
#> Elements:
#> 
#> [[1]]
#> $has
#> [1] TRUE
#> 
#> $priority
#> [1] 5
#> 
#> 
#> [[2]]
#> $has
#> [1] TRUE
#> 
#> $priority
#> [1] 1
#> 
#> 
#> [[3]]
#> $has
#> [1] TRUE
#> 
#> $priority
#> [1] 3
#> 
#>