Fix compute_partitions() in cluster_cells.R.

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: monocle3
 Title: Clustering, Differential Expression, and Trajectory Analysis for
     Single-Cell RNA-Seq
-Version: 1.4.13
+Version: 1.4.14
 Authors@R: c(
     person(given = "Hannah",
            family = "Pliner",

R/cluster_cells.R

@@ -599,6 +599,8 @@ compute_partitions <- function(g,
                                optim_res,
                                qval_thresh=0.05,
                                verbose = FALSE){
+  # The cells membership may have information about the
+  # clusters to which cells' nearest neighbors belong.
   cell_membership <- as.factor(igraph::membership(optim_res))
   membership_matrix <- Matrix::sparse.model.matrix( ~ cell_membership + 0)
   num_links <- Matrix::t(membership_matrix) %*%
@@ -617,6 +619,9 @@ compute_partitions <- function(g,
 
   num_links <- num_links_ij / total_edges
 
+  # Deal with zero total edges.
+  num_links[is.nan(num_links)] <- 0
+
   cluster_mat <- matrix(stats::p.adjust(cluster_mat),
                         nrow=length(louvain_modules),
                         ncol=length(louvain_modules))