simap: Map Functions Over Glycan Structure Vectors with Indices

In glyrepr: Representation for Glycan Compositions and Structures

Map Functions Over Glycan Structure Vectors with Indices

Description

These functions apply a function to each unique structure in a glycan structure vector along with their corresponding indices, taking advantage of hash-based deduplication to avoid redundant computation. Similar to purrr imap functions, but optimized for glycan structure vectors.

Usage

simap(.x, .f, ...)

simap_vec(.x, .f, ..., .ptype = NULL)

simap_lgl(.x, .f, ...)

simap_int(.x, .f, ...)

simap_dbl(.x, .f, ...)

simap_chr(.x, .f, ...)

simap_structure(.x, .f, ...)

Arguments

.x	A glycan structure vector (glyrepr_structure).
.f	A function that takes an igraph object (from .x) and an index/name, returning a result. Can be a function, purrr-style lambda (~ paste(.x, .y)), or a character string naming a function. A structure with floating metadata is passed as one annotated graph.
...	Additional arguments passed to .f.
.ptype	A prototype for the return type (for simap_vec).

Details

These functions only compute .f once for each unique combination of structure and corresponding index/name, then map the results back to the original vector positions. This is much more efficient than applying .f to each element individually when there are duplicate structures.

simap_structure() reuses unchanged graphs and validates and canonicalizes changed graphs returned by .f. A callback that changes vertex identities or components of a floating structure must also update its floating_parts and floating_substituents metadata.

IMPORTANT PERFORMANCE NOTE: Due to the inclusion of position indices, simap functions have O(total_structures) time complexity because each position creates a unique combination, even with identical structures.

Alternative: Consider smap() functions if position information is not required.

The index passed to .f is the position in the original vector (1-based). If the vector has names, the names are passed instead of indices.

Return Types:

• simap(): Returns a list with the same length as .x

• simap_vec(): Returns an atomic vector with the same length as .x

• simap_lgl(): Returns a logical vector

• simap_int(): Returns an integer vector

• simap_dbl(): Returns a double vector

• simap_chr(): Returns a character vector

• simap_structure(): Returns a new glycan structure vector (.f must return igraph objects)

Value

• simap(): A list

• simap_vec(): An atomic vector of type specified by .ptype

• simap_lgl(): Returns a logical vector

• simap_int(): Returns an integer vector

• simap_dbl(): Returns a double vector

• simap_chr(): Returns a character vector

• simap_structure(): A new glyrepr_structure object

Examples

# Create structure vectors with duplicates
core1 <- o_glycan_core_1()
core2 <- n_glycan_core()
structures <- c(core1, core2, core1)  # core1 appears twice

# Map a function that uses both structure and index
simap_chr(structures, function(g, i) paste0("Structure_", i, "_vcount_", igraph::vcount(g)))

# Use purrr-style lambda functions
simap_chr(structures, ~ paste0("Pos", .y, "_vertices", igraph::vcount(.x)))

glyrepr documentation built on Sept. 22, 2026, 5:09 p.m.