Chapter 6 Seurat Individual Batch Effect Exploration

library(Seurat)
library(tidyverse)
library(magrittr)
library(data.table)

6.1 Descripiton

Explore the individual batch effect by

• Dimplot split by individual

• Fractions of individuals per cluster

6.2 Load seurat object

combined <- get(load('data/Demo_CombinedSeurat_SCT_Preprocess.RData'))

6.3 Explore individual distribution by Dimplot

Idents(object = combined) <- 'Individual'
DimPlot(object = combined, reduction = "umap", label = T) 

DimPlot(object = combined, reduction = "tsne", label = T) 

6.4 Calculate individual distribution per cluster with different resolution

df <- data.table(combined@meta.data)
sel.meta <- c("Individual", str_c('SCT_snn_res.', c(1, 1.5, 1.8)))
df <- df[, sel.meta, with = FALSE]


df[, 2:4] %>% imap(~ {
    freq1 <- df[, .N, keyby = .(.x, Individual)]
    freq1[, total := sum(N), by = .(.x)]
    freq1[, ratio := N / total]
    
    linesize = .35
    fontsize = 8
    
    ggplot(freq1, aes(fill = Individual, y = ratio, x = .x)) +
      geom_bar(position = "stack", stat = "identity") +
      scale_fill_brewer(palette = "Dark2") +
      xlab('Clsuter') +
      ggtitle(.y) +
      scale_y_continuous(breaks = seq(0, 1, 0.1),
                         expand = c(0, 0),
                         name = 'Percentage') +
      theme_bw() +
      theme(
        panel.grid.major.x = element_blank(),
        panel.grid.major.y = element_blank(),
        panel.grid.minor = element_blank(),
        strip.background = element_blank(),
        panel.border = element_rect(size = linesize),
        axis.ticks = element_blank(),
        axis.text.x = element_text(size = 5)
      ) +
      coord_flip()
})

## $SCT_snn_res.1

## 
## $SCT_snn_res.1.5

## 
## $SCT_snn_res.1.8