make_heat_map_from_physeq: Internal function to draw heatmap from a physeq object.
In TBrach/MicrobiomeX: eXtended Functions for Microbiome Analysis and Visualization

Internal function to draw heatmap from a physeq object.

make_heat_map_from_physeq(physeq, taxa_data = NULL, group, block = NULL,
  compare = NULL, max_abundance_for_color = NULL, log_transform = FALSE,
  border_color = "grey60", filename = NA, tax_labels = NULL,
  tax_order = NULL, show_rownames = TRUE, cellwidth = NA,
  cellheight = NA, gaps_col = NULL, gradient_steps, custom_palette = NULL)

`physeq`	Phyloseq object
`taxa_data`	Taxa annotation to show.
`group`	Name of column in sample metadata to group samples on (1st layer).
`block`	Name of column in sample metadata to subgroup samples on (2nd layer).
`compare`	Vector of values in `group` column to compare (e.g., HFD vs Control).
`max_abundance_for_color`	Maximum abundance to use in the color scale of 50 levels. If null, the 99.5th percentile in the data is used. If maximum value in the data is higher than this, this will be level 49 and max will be level 50.
`border_color`	Border color for the heatmap cells.
`filename`	Name of file to save the heatmap figure.
`tax_labels`	Character vector of names to be shown for each taxon. If NULL, names in the physeq object will be used.
`tax_order`	Character vector of the original taxon names in the order you want them shown. If NULL, order in tax_labels will be used.
`gradient_steps`	The steps for the 5-phase 50-level gradient is drawn.