download.file(paste0(url, "/", cluster_merging1_filename), 
  destfile = cluster_merging1_filename, mode = "wb")

original_cluster  new_cluster
1                 1 B-cells IgM+
2                 2     surface-
3                 3     NK cells
4                 4  CD8 T-cells
5                 5 B-cells IgM-
6                 6    monocytes
7                 7    monocytes
8                 8  CD8 T-cells
9                 9  CD8 T-cells
10               10    monocytes
11               11    monocytes
12               12  CD4 T-cells
13               13           DC
14               14  CD8 T-cells
15               15  CD4 T-cells
16               16           DC
17               17  CD4 T-cells
18               18  CD4 T-cells
19               19  CD4 T-cells
20               20  CD4 T-cells

## Convert to factor with merged clusters in desired order

levels_clusters_merged <- c("B-cells IgM+", "B-cells IgM-", "CD4 T-cells", 
  "CD8 T-cells", "DC", "NK cells", "monocytes", "surface-")

cluster_merging1$new_cluster <- factor(cluster_merging1$new_cluster, 
  levels = levels_clusters_merged)