Percentage distribution of cells in all clusters based on their treatment condition?
Here is a solution using dplyr and ggplot2:
library(Seurat) 
library(dplyr)
library(ggplot2)

meta.data &lt;- pbmc_small[[]]

# create random classifications for the sake of this example
meta.data$condition &lt;- sample(c('A', 'B', 'C'), nrow(meta.data), replace = TRUE)

counts &lt;- group_by(meta.data, condition, res.1) %&gt;% summarise(count = n())

ggplot(counts, aes(res.1, count, fill = condition)) +
  geom_bar(stat = 'identity')