Visualizing taxonomic abundances with heat trees in metacoder can be done using the following steps:

1. Load the libraries and input files:

library(metacoder)
library(RColorBrewer)
biom_file <- file.path(getwd(), "datasets", "ch5", "rich_high_count_otu.biom")
taxdata <- parse_qiime_biom(biom_file)

2. Pass customization options to the tree-drawing function:

heat_tree(taxdata, 
    node_label = taxon_names, 
    node_size = n_obs, 
    node_color = n_supertaxa, 
    layout = "gem", 
    title = "sample heat tree", 
    node_color_axis_label = "Number of Supertaxa", 
    node_size_axis_label = "Number of OTUs", 
    node_color_range = RColorBrewer::brewer.pal(5, "Greens")
)