#' Plot the gene expression of a list of genes in a SCE object
#'
#' This function plots the expression of one or more genes as a violin plot,
#' over a user defined category, typically a cell type annotation.
#'
#' @param sce [SummarizedExperiment-class][SummarizedExperiment::SummarizedExperiment-class] object
#' @param genes A `list()` of `character(1)` specifying the genes to plot, this should match the format of `rownames(sce)`
#' @param assay_name A `character(1)` specifying the name of the
#' [assay()][SummarizedExperiment::SummarizedExperiment-class] in the
#' `sce` object to use to rank expression values. Defaults to `logcounts` since
#' it typically contains the normalized expression values.
#'
#' @param category A `character(1)` specifying the name of the categorical variable
#' to group the cells or nuclei by. Defaults to `cellType`.
#' @param color_pal A named `character(1)` vector that contains a color pallet matching the `category` values.
#' @param title A `character(1)` to title the plot
#' @param plot_points A logical indicating whether to plot points over the violin,
#' defaults to `FALSE` as these often become over plotted and quite large (especially when saved as PDF)
#' @param ncol = Number of columns for the facet in the final plot. Defaults to 2.
#'
#' @return A `ggplot()` violin plot for selected genes
#' @export
#'
#' @examples
#' ## Using Symbol as rownames makes this more human readable
#' plot_gene_express(sce = sce_ab, genes = c("G-D1_A"))
#'
#' if (!exists("sce_DLPFC_example")) sce_DLPFC_example <- fetch_deconvo_data("sce_DLPFC_example")
#' ## plot expression of two genes
#' plot_gene_express(sce = sce_DLPFC_example, category = "cellType_broad_hc", genes = c("GAD2", "CD22"))
#'
#' ## plot points - note this creates large images and is easy to over plot
#' plot_gene_express(sce = sce_DLPFC_example, category = "cellType_broad_hc", genes = c("GAD2", "CD22"), plot_points = TRUE)
#'
#' ## Add title
#' plot_gene_express(sce = sce_DLPFC_example, category = "cellType_broad_hc", genes = c("GAD2", "CD22"), title = "My Genes")
#'
#' @family expression plotting functions
#'
plot_gene_express <- function(sce,
genes,
assay_name = "logcounts",
category = "cellType",
color_pal = NULL,
title = NULL,
plot_points = FALSE,
ncol = 2) {
stopifnot(any(genes %in% rownames(sce)))
if (!category %in% colnames(colData(sce))) {
stop(
category,
"' is not a column name in colData(sce), check that `category` matches this sce",
call. = FALSE
)
}
stopifnot(assay_name %in% SummarizedExperiment::assayNames(sce))
value <- median <- NULL
category_df <- as.data.frame(colData(sce))[, category, drop = FALSE]
expression_long <- reshape2::melt(as.matrix(SummarizedExperiment::assays(sce)[[assay_name]][genes, , drop = FALSE]))
category <- category_df[expression_long$Var2, ]
expression_long <- cbind(expression_long, category)
expression_violin <- ggplot(data = expression_long, aes(x = category, y = value)) +
# ggplot2::geom_violin(aes(fill = category), scale = "width") +
ggplot2::facet_wrap(~Var1, ncol = ncol) +
ggplot2::labs(
y = paste0("Expression (", assay_name, ")"),
title = title
) +
ggplot2::theme_bw() +
ggplot2::theme(
legend.position = "None",
axis.title.x = ggplot2::element_blank(),
axis.text.x = ggplot2::element_text(angle = 90, hjust = 1),
strip.text.x = ggplot2::element_text(face = "italic")
)
if (plot_points) {
expression_violin <- expression_violin +
ggplot2::geom_violin(aes(color = category), scale = "width") +
ggplot2::geom_jitter(aes(color = category),
position = ggplot2::position_jitter(seed = 1, width = 0.2), size = .5
) +
ggplot2::stat_summary(
fun = median,
geom = "crossbar",
width = 0.3
)
if (!is.null(color_pal)) expression_violin <- expression_violin + ggplot2::scale_color_manual(values = color_pal)
return(expression_violin)
}
expression_violin <- expression_violin +
ggplot2::geom_violin(aes(fill = category), scale = "width") +
ggplot2::stat_summary(
fun = median,
geom = "crossbar",
width = 0.3
)
if (!is.null(color_pal)) expression_violin <- expression_violin + ggplot2::scale_fill_manual(values = color_pal)
# expression_violin
return(expression_violin)
}
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