error fix in SelectNetworkGenes

      cur

    }))

    print('size')

    print(dim(expr_mat))

    group_gene_list <- list()

    if(!is.null(group.by)){

      # identify genes that are expressed

        cur_expr <- expr_mat[,seurat_obj@meta.data[[group.by]] == cur_group]

        print(dim(cur_expr))

        gene_filter <- rowSums(cur_expr) >= round(fraction*ncol(cur_expr));

        gene_filter <- rowSums(as.matrix(cur_expr)) >= round(fraction*ncol(cur_expr));

        group_gene_list[[cur_group]] <- rownames(seurat_obj)[gene_filter]

      }

      gene_list <- unique(unlist(group_gene_list))

    } else{

      # identify genes that are expressed in at least some fraction of cells

      print('before size')

      print(class(expr_mat))

      print(dim(expr_mat))

      # gene_filter <- rowSums(expr_mat) >= round(fraction*ncol(seurat_obj));

      gene_filter <- rowSums(as.matrix(expr_mat)) >= round(fraction*ncol(seurat_obj));

      print('after')

      gene_list <- rownames(seurat_obj)[gene_filter]

    }