fix: Fix alpha_centrality() crash when weights is a custom attribute name (#2403)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: krlmlr <[email protected]>

Author: Copilot

R/centrality.R

@@ -2018,7 +2018,7 @@ alpha.centrality.dense <- function(
     attr <- NULL
   } else if (is.character(weights) && length(weights) == 1) {
     ## name of an edge attribute, nothing to do
-    attr <- "weight"
+    attr <- weights
   } else if (any(!is.na(weights))) {
     ## weights != NULL and weights != rep(NA, x)
     graph <- set_edge_attr(graph, "weight", value = as.numeric(weights))
@@ -2065,7 +2065,7 @@ alpha.centrality.sparse <- function(
     attr <- NULL
   } else if (is.character(weights) && length(weights) == 1) {
     ## name of an edge attribute, nothing to do
-    attr <- "weight"
+    attr <- weights
   } else if (any(!is.na(weights))) {
     ## weights != NULL and weights != rep(NA, x)
     graph <- set_edge_attr(graph, "weight", value = as.numeric(weights))

tests/testthat/test-centrality.R

@@ -658,6 +658,22 @@ test_that("weighted sparse alpha_centrality() works", {
   expect_equal(ac3, c(vcount(star), 1, 1, 1, 1, 1, 1, 1, 1, 1))
 })
 
+test_that("alpha_centrality() works with custom weight attribute names", {
+  star <- make_star(10)
+  E(star)$myweight <- sample(ecount(star))
+
+  # Test sparse version with custom attribute name
+  ac_sparse <- alpha_centrality(star, weights = "myweight", sparse = TRUE)
+  expect_equal(ac_sparse, c(46, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+
+  # Test dense version with custom attribute name
+  ac_dense <- alpha_centrality(star, weights = "myweight", sparse = FALSE)
+  expect_equal(ac_dense, c(46, 1, 1, 1, 1, 1, 1, 1, 1, 1))
+
+  # Ensure both versions give the same result
+  expect_equal(ac_sparse, ac_dense)
+})
+
 test_that("undirected alpha_centrality() works, #653", {
   g <- make_ring(10)