view filter_cells.R @ 3:5407dc697e24 draft default tip

planemo upload for repository https://github.com/ARTbio/tools-artbio/tree/main/tools/gsc_filter_cells commit fdfb8deb1e770c824fcd1e127c2e3faa4e0cf35e

# First step of the signature-based workflow
# Remove low quality cells below a user-fixed cutoff of
# percentiles or raw values of number of genes detected or
# total aligned reads

options(show.error.messages = FALSE,
  error = function() {
    cat(geterrmessage(), file = stderr())
    q("no", 1, FALSE)
  }
)

loc <- Sys.setlocale("LC_MESSAGES", "en_US.UTF-8")
warnings()

library(optparse)
library(ggplot2)

# Arguments
option_list <- list(
  make_option(c("-f", "--file"), default = NA, type = "character",
              help = "Input file that contains values to filter"),
  make_option("--sep", default = "\t", type = "character",
              help = "File column separator [default : '%default' ]"),
  make_option("--percentile_genes", default = 0, type = "integer",
              help = "nth Percentile of the number of genes detected by a cell distribution [default : '%default' ]"),
  make_option("--percentile_counts", default = 0, type = "integer",
              help = "nth Percentile of the total counts per cell distribution [default : '%default' ]"),
  make_option("--absolute_genes", default = 0, type = "integer",
              help = "Remove cells that did not express at least this number of genes [default : '%default' ]"),
  make_option("--absolute_counts", default = 0, type = "integer",
              help = "Number of transcript threshold for cell filtering [default : '%default' ]"),
  make_option("--manage_cutoffs", default = "intersect", type = "character",
              help = "combine or intersect cutoffs for filtering"),
  make_option("--pdfplot", type = "character",
              help = "Path to pdf file of the plots"),
  make_option("--output", type = "character",
              help = "Path to tsv file of filtered cell data"),
  make_option("--output_metada", type = "character",
              help = "Path to tsv file of filtered cell metadata")
)
opt <- parse_args(OptionParser(option_list = option_list),
  args = commandArgs(trailingOnly = TRUE)
)
if (opt$sep == "tab") {
  opt$sep <- "\t"
}
if (opt$sep == "comma") {
  opt$sep <- ","
}
if (opt$sep == "space") {
  opt$sep <- " "
}


## check consistency of filtering options

# if input parameters are not consistent (one or either method, not both), no filtering
if ((opt$percentile_counts > 0) && (opt$absolute_counts > 0)) {
  opt$percentile_counts <- 0
}

# if input parameters are not consistent (one or either method, not both), no filtering
if ((opt$percentile_genes > 0) && (opt$absolute_genes > 0)) {
  opt$percentile_genes <- 0
}

# Import datasets
data_counts <- read.delim(
  opt$file,
  header = TRUE,
  stringsAsFactors = FALSE,
  sep = opt$sep,
  check.names = FALSE,
  row.names = 1
)

QC_metrics <- data.frame(cell_id = colnames(data_counts),
                         nGenes = colSums(data_counts != 0),  # nGenes is Number of detected genes for each cell
                         total_counts = colSums(data_counts),  # total_counts is Total counts per cell
                         stringsAsFactors = FALSE)


plot_hist <- function(mydata, variable, title, cutoff) {
  mybinwidth <- round(max(mydata[, variable]) * 5 / 100)
  mylabel <- paste0("cutoff= ", cutoff)
  hist_plot <- ggplot(as.data.frame(mydata[, variable]),
                      aes(x = mydata[, variable], colour = I("white"))) +
    geom_histogram(binwidth = mybinwidth) +
    labs(title = title, x = variable, y = "count") +
    scale_x_continuous() +
    geom_vline(xintercept = cutoff) +
    annotate(geom = "text",
             x = cutoff + mybinwidth, y = 1,
             label = mylabel, color = "white")
  plot(hist_plot)
  return
}

# returns the highest value such as the sum of the ordered values including this highest
# value is lower (below) than the percentile threshold (n)
percentile_cutoff <- function(n, qcmetrics, variable, plot_title, ...) {
  p <- n / 100
  percentile_threshold <- quantile(qcmetrics[, variable], p)[[1]]
  plot_hist(qcmetrics,
            variable,
            plot_title,
            percentile_threshold)
  return(percentile_threshold)
}

pdf(file = opt$pdfplot)

# Determine thresholds based on percentile

if (opt$percentile_counts > 0) {
  counts_threshold <- percentile_cutoff(opt$percentile_counts,
                                        QC_metrics,
                                        "total_counts",
                                        "Histogram of Aligned read counts per cell")
} else {
  counts_threshold <- opt$absolute_counts
  plot_hist(QC_metrics,
            variable = "total_counts",
            title = "Histogram of Total counts per cell",
            cutoff = counts_threshold)
}

if (opt$percentile_genes > 0) {
  genes_threshold <- percentile_cutoff(opt$percentile_genes,
                                       QC_metrics,
                                       "nGenes",
                                       "Histogram of Number of detected genes per cell")
} else {
  genes_threshold <- opt$absolute_genes
  plot_hist(QC_metrics,
            variable = "nGenes",
            title = "Histogram of Number of detected genes per cell",
            cutoff = genes_threshold)
}

# Filter out rows below thresholds (genes and read counts)
if (opt$manage_cutoffs == "union") {
  QC_metrics$filtered <- (QC_metrics$nGenes < genes_threshold) | (QC_metrics$total_counts < counts_threshold)
} else {
  QC_metrics$filtered <- (QC_metrics$nGenes < genes_threshold) & (QC_metrics$total_counts < counts_threshold)
}

## Plot the results

# Determine title from the parameter logics
if (opt$percentile_counts > 0) {
  part_one <- paste0("Cells with aligned reads counts below the ",
                     opt$percentile_counts,
                     "th percentile of aligned read counts")
} else {
  part_one <- paste0("Cells with aligned read counts below ",
                     opt$absolute_counts)
}

if (opt$percentile_genes > 0) {
  part_two <- paste0("with number of detected genes below the ",
                     opt$percentile_genes,
                     "th percentile of detected gene counts")
} else {
  part_two <- paste0("with number of detected genes below ",
                     opt$absolute_genes)
}

if (opt$manage_cutoffs == "intersect") {
  conjunction <- " and\n"
} else {
  conjunction <- " or\n"
}

# plot with ggplot2
ggplot(QC_metrics, aes(nGenes, total_counts, colour = filtered)) +
  geom_point() +
  scale_y_log10() +
  scale_colour_discrete(name  = "",
    breaks = c(FALSE, TRUE),
    labels = c(paste0("Not filtered (", table(QC_metrics$filtered)[1], " cells)"),
               paste0("Filtered (", table(QC_metrics$filtered)[2], " cells)"))
  ) +
  xlab("Detected genes per cell") +
  ylab("Aligned reads per cell (log10 scale)") +
  geom_vline(xintercept = genes_threshold) +
  geom_hline(yintercept = counts_threshold) +
  ggtitle(paste0(part_one, conjunction, part_two, "\nwere filtered out")) +
  theme(plot.title = element_text(size = 8, face = "bold"))

dev.off()

# Retrieve identifier of kept_cells
kept_cells <- QC_metrics$cell_id[!QC_metrics$filtered]

data_counts <- data.frame(Genes = rownames(data_counts[, kept_cells]),
                          data_counts[, kept_cells],
                          check.names = FALSE)

# Save filtered cells
write.table(data_counts,
  opt$output,
  sep = "\t",
  quote = FALSE,
  col.names = TRUE,
  row.names = FALSE
)

# Add QC metrics of filtered cells to a metadata file
metadata <- QC_metrics

# Save the metadata (QC metrics) file
write.table(metadata,
  opt$output_metada,
  sep = "\t",
  quote = FALSE,
  col.names = TRUE,
  row.names = FALSE
)