R Under development (unstable) (2024-05-23 r86608 ucrt) -- "Unsuffered Consequences"
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Platform: x86_64-w64-mingw32/x64

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> genhash <- function (len = 10) {
+     paste0 (sample (c (letters, LETTERS, 0:9), size = len), collapse = "")
+ }
> 
> sf_to_sc <- function (x) {
+ 
+     pts <- do.call (rbind, x$geometry)
+     pts <- data.frame (
+         "x_" = pts [, 1],
+         "y_" = pts [, 2],
+         "vertex_" = rownames (pts),
+         stringsAsFactors = FALSE
+     )
+     pts <- pts [which (!duplicated (pts)), ]
+ 
+     edge <- lapply (x$geometry, function (i) {
+         cbind (
+             rownames (i) [1:(nrow (i) - 1)],
+             rownames (i) [2:nrow (i)]
+         )
+     })
+     for (e in seq (edge)) {
+         edge [[e]] <- cbind (edge [[e]], names (x$geometry) [e])
+     }
+     edge <- data.frame (do.call (rbind, edge), stringsAsFactors = FALSE)
+     edge$edge_ <- vapply (
+         seq (nrow (edge)), function (i) genhash (10),
+         character (1)
+     )
+ 
+     object_link_edge <- data.frame (
+         edge_ = edge$edge_,
+         object_ = edge$X3,
+         native_ = TRUE,
+         stringsAsFactors = FALSE
+     )
+     edge <- data.frame (
+         ".vx0" = edge$X1,
+         ".vx1" = edge$X2,
+         "edge_" = edge$edge_,
+         stringsAsFactors = FALSE
+     )
+ 
+     x_no_g <- x
+     x_no_g$geometry <- NULL
+     osm_id <- as.character (x_no_g$osm_id)
+     x_no_g$osm_id <- NULL
+     for (i in names (x_no_g)) {
+         x_no_g [[i]] <- as.character (x_no_g [[i]])
+     }
+     x_no_g <- as.list (x_no_g)
+     x_no_g <- lapply (x_no_g, function (i) {
+         res <- cbind (osm_id, i)
+         res [which (!is.na (res [, 2])), , drop = FALSE]
+     })
+     for (i in seq (x_no_g)) {
+         x_no_g [[i]] <- cbind (x_no_g [[i]], names (x_no_g) [i])
+     }
+     x_no_g <- data.frame (do.call (rbind, x_no_g),
+         stringsAsFactors = FALSE
+     )
+     object <- data.frame (
+         "object_" = x_no_g$osm_id,
+         key = x_no_g$V3,
+         value = x_no_g$i,
+         stringsAsFactors = FALSE
+     )
+     object <- object [order (object$object_), ]
+ 
+     res <- list (
+         nodes = NULL,
+         object = object,
+         object_link_edge = object_link_edge,
+         edge = edge,
+         vertex = pts
+     )
+     class (res) <- c ("SC", "sc", "osmdata_sc")
+     return (res)
+ }
> 
> proc.time()
   user  system elapsed 
   0.21    0.07    0.25