smap2: Map Functions Over Two Glycan Structure Vectors

In glyrepr: Representation for Glycan Compositions and Structures

Map Functions Over Two Glycan Structure Vectors

Description

These functions apply a function to each unique structure combination in two glycan structure vectors, taking advantage of hash-based deduplication to avoid redundant computation. Similar to purrr map2 functions, but optimized for glycan structure vectors.

Usage

smap2(.x, .y, .f, ...)

smap2_vec(.x, .y, .f, ..., .ptype = NULL)

smap2_lgl(.x, .y, .f, ...)

smap2_int(.x, .y, .f, ...)

smap2_dbl(.x, .y, .f, ...)

smap2_chr(.x, .y, .f, ...)

smap2_structure(.x, .y, .f, ...)

Arguments

.x	A glycan structure vector (glyrepr_structure).
.y	A vector of the same length as .x, or length 1 (will be recycled).
.f	A function that takes an igraph object (from .x) and a value (from .y) and returns a result. Can be a function, purrr-style lambda (~ .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 smap2_vec).

Details

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

smap2_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.

NA Handling: NA elements in .x are preserved in the output - the function is not applied to NA positions, and the corresponding results are set to NA.

Return Types:

• smap2(): Returns a list with the same length as .x

• smap2_vec(): Returns an atomic vector with the same length as .x

• smap2_lgl(): Returns a logical vector

• smap2_int(): Returns an integer vector

• smap2_dbl(): Returns a double vector

• smap2_chr(): Returns a character vector

• smap2_structure(): Returns a new glycan structure vector (.f must return igraph objects)

Value

• smap2(): A list

• smap2_vec(): An atomic vector of type specified by .ptype

• smap2_lgl/int/dbl/chr(): Atomic vectors of the corresponding type

• smap2_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
weights <- c(1.0, 2.0, 1.0)  # corresponding weights

# Map a function that uses both structure and weight
smap2_dbl(structures, weights, function(g, w) igraph::vcount(g) * w)

# Use purrr-style lambda functions
smap2_dbl(structures, weights, ~ igraph::vcount(.x) * .y)

# Test with recycling (single weight for all structures)
smap2_dbl(structures, 2.5, ~ igraph::vcount(.x) * .y)

# Map a function that modifies structure based on second argument
# This example adds a graph attribute instead of modifying topology
add_weight_attr <- function(g, weight) {
  igraph::set_graph_attr(g, "weight", weight)
}
weights_to_add <- c(1.5, 2.5, 1.5)
smap2_structure(structures, weights_to_add, add_weight_attr)

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