#' @title Principle component analysis for gene Data
#'
#' @description Performs principle component analysis using gene expression values.
#'
#' @param MarvelObject Marvel object. S3 object generated from \code{ComputePSI} function.
#' @param sample.ids Character strings. Specific cells to plot.
#' @param cell.group.column Character string. The name of the sample metadata column in which the variables will be used to label the cell groups on the PCA.
#' @param cell.group.order Character string. The order of the variables under the sample metadata column specified in \code{cell.group.column} to appear in the PCA cell group legend.
#' @param cell.group.colors Character string. Vector of colors for the cell groups specified for PCA analysis using \code{cell.type.columns} and \code{cell.group.order}. If not specified, default \code{ggplot2} colors will be used.
#' @param min.cells Numeric value. The minimum no. of cells expressing the gene to be included for analysis.
#' @param features Character string. Vector of \code{gene_id} for analysis. Should match \code{gene_id} column of \code{MarvelObject$GeneFeature}.
#' @param point.size Numeric value. Size of data points on reduced dimension space.
#' @param point.alpha Numeric value. Transparency of the data points on reduced dimension space. Take any values between 0 to 1. The smaller the value, the more transparent the data points will be.
#' @param point.stroke Numeric value. The thickness of the outline of the data points. The larger the value, the thicker the outline of the data points.
#' @param pcs Numeric vector. The principal components (PCs) to plot. Default is the first two PCs, i.e., \code{c(1,2)}. If a vector of 3 is specified, a 3D scatterplot is returned.
#' @param mode Character string. Specify \code{"pca"} for linear dimension reduction analysis or \code{"umap"} for non-linear dimension reduction analysis. Specify \code{"elbow.plot"} to return eigen values. Default is \code{"pca"}.
#' @param seed.umap Numeric value. Only applicable when \code{mode} set to \code{"umap"}. To sure reproducibility of analysis. Default value is \code{42}.
#' @param npc.umap Numeric value. Only applicable when \code{mode} set to \code{"umap"}. Incidate the number of PCs to include for UMAP. Default value is \code{30}.
#' @param remove.outliers Logical value. If set to \code{TRUE}, outliers will be removed. Outliers defined as data points beyond 1.5 times the interquartile range (IQR) from the 1st and 99th percentile. Default is \code{FALSE}.
#' @param npc.elbow.plot Numeric value. Only applicable when \code{mode} set to \code{"elbow.plot"}. Incidate the number of PCs to for elbow plot. Default value is \code{50}.
#'
#' @return An object of class S3 containing with new slots \code{MarvelObject$PCA$Exp$Results}, \code{MarvelObject$PCA$Exp$Plot}, and \code{MarvelObject$PCA$Exp$Plot.Elbow}.
#'
#' @importFrom plyr join
#' @import methods
#' @import ggplot2
#' @importFrom grDevices hcl
#'
#' @export
#'
#' @examples
#' marvel.demo <- readRDS(system.file("extdata/data", "marvel.demo.rds", package="MARVEL"))
#'
#' # Define genes for analysis
#' gene_ids <- marvel.demo$Exp$gene_id
#'
#' # PCA
#' marvel.demo <- RunPCA.Exp(MarvelObject=marvel.demo,
#' sample.ids=marvel.demo$SplicePheno$sample.id,
#' cell.group.column="cell.type",
#' cell.group.order=c("iPSC", "Endoderm"),
#' min.cells=5,
#' features=gene_ids,
#' point.size=2
#' )
#'
#' # Check outputs
#' head(marvel.demo$PCA$Exp$Results$ind$coord)
#' marvel.demo$PCA$Exp$Plot
RunPCA.Exp <- function(MarvelObject, sample.ids=NULL, cell.group.column, cell.group.order=NULL, cell.group.colors=NULL,
features, min.cells=25,
point.size=0.5, point.alpha=0.75, point.stroke=0.1,
pcs=c(1,2),
mode="pca", seed.umap=42, npc.umap=30,
remove.outliers=FALSE, npc.elbow.plot=50
) {
# Define arguments
MarvelObject <- MarvelObject
df <- MarvelObject$Exp
df.pheno <- MarvelObject$SplicePheno
df.feature <- MarvelObject$GeneFeature
sample.ids <- sample.ids
cell.group.column <- cell.group.column
cell.group.order <- cell.group.order
cell.group.colors <- cell.group.colors
features <- features
min.cells <- min.cells
point.size <- point.size
point.alpha <- point.alpha
point.stroke <- point.stroke
mode <- mode
seed.umap <- seed.umap
npc.umap <- npc.umap
# Example arguments
#MarvelObject <- marvel
#df <- MarvelObject$Exp
#df.pheno <- MarvelObject$SplicePheno
#df.feature <- MarvelObject$GeneFeature
#sample.ids <- NULL
#cell.group.column <- cell.group.column
#cell.group.order <- cell.group.order
#cell.group.colors <- c("red", "blue", "lightgreen", "purple")
#features <- gene_ids
#min.cells <- 25
#point.size <- 1.5
#point.alpha <- 0.75
#point.stroke <- 0.1
#pcs <- c(1,2)
#mode <- "umap"
#seed.umap <- 42
#npc.umap <- 30
######################################################################
# Create row names for matrix
row.names(df) <- df$gene_id
df$gene_id <- NULL
# Rename cell group label/impute columns
names(df.pheno)[which(names(df.pheno)==cell.group.column)] <- "pca.cell.group.label"
# Subset relevant cells: overall
if(!is.null(sample.ids[1])) {
df.pheno <- df.pheno[which(df.pheno$sample.id %in% sample.ids), ]
}
# Subset relevant cells
# Check if cell group order is defined
if(is.null(cell.group.order[1])) {
cell.group.order <- unique(df.pheno$pca.cell.group.label)
}
# Cell group
index <- which(df.pheno$pca.cell.group.label %in% cell.group.order)
df.pheno <- df.pheno[index, ]
# Subset matrix
df <- df[, df.pheno$sample.id]
# Set factor levels
levels <- intersect(cell.group.order, unique(df.pheno$pca.cell.group.label))
df.pheno$pca.cell.group.label <- factor(df.pheno$pca.cell.group.label, levels=levels)
# Subset features to reduce
df.feature <- df.feature[which(df.feature$gene_id %in% features), ]
df <- df[df.feature$gene_id, ]
# Subset events with sufficient cells
. <- apply(df, 1, function(x) {sum(x != 0)})
index.keep <- which(. >= min.cells)
df <- df[index.keep, ]
df.feature <- df.feature[which(df.feature$gene_id %in% row.names(df)), ]
# Define n PCs to return
if(nrow(df.pheno) >= 50) {
npc <- 50
} else {
npc <- nrow(df)
}
# Reduce dimension
res.pca <- FactoMineR::PCA(as.data.frame(t(df)), scale.unit=TRUE, ncp=npc, graph=FALSE)
##############################################
# Return elbow plot
if(mode=="elbow.plot") {
# Retrieve eigenvalues
results.eigen <- as.data.frame(factoextra::get_eigenvalue(res.pca))
. <- data.frame("pc"=row.names(results.eigen))
results.eigen <- cbind.data.frame(., results.eigen)
results.eigen$pc <- gsub("Dim.", "", results.eigen$pc, fixed=TRUE)
results.eigen$pc <- as.numeric(results.eigen$pc)
# Subset dimensions
index <- c(1:npc.elbow.plot)
results.eigen <- results.eigen[index, ]
# Dot plot
# Definition
data <- results.eigen
x <- data$pc
y <- data$variance.percent
maintitle <- ""
xtitle <- "PC"
ytitle <- "Variance explained (%)"
# Plot
plot <- ggplot() +
geom_point(data, mapping=aes(x=x, y=y), fill="black", size=1) +
labs(title=maintitle, x=xtitle, y=ytitle) +
theme(panel.grid.major=element_blank(),
panel.grid.minor=element_blank(),
panel.background=element_blank(),
plot.title = element_text(size=12, hjust=0.5),
axis.line=element_line(colour = "black"),
axis.title=element_text(size=12),
axis.text.x=element_text(size=10, colour="black"),
axis.text.y=element_text(size=10, colour="black")
)
# Save into new slot
MarvelObject$PCA$Exp$EigenValues <- results.eigen
MarvelObject$PCA$Exp$ElbowPlot <- plot
# Return MARVEL object
return(MarvelObject)
}
##############################################
# Define no. of columns for legends
n.groups <- length(levels(df.pheno$pca.cell.group.label))
ncol.legends <- ifelse(n.groups < 6, 1, 2)
# Scatterplot: 2D or 3D
if(mode=="pca") {
if(length(pcs)==2){
# Definition
data <- as.data.frame(res.pca$ind$coord)
x <- data[,pcs[1]]
y <- data[,pcs[2]]
z <- df.pheno$pca.cell.group.label
maintitle <- paste(nrow(df), " genes", sep="")
xtitle <- paste("PC", pcs[1], " (", round(factoextra::get_eigenvalue(res.pca)[pcs[1],2], digits=2), "%)" ,sep="")
ytitle <- paste("PC", pcs[2], " (", round(factoextra::get_eigenvalue(res.pca)[pcs[2],2], digits=2), "%)" ,sep="")
legendtitle <- "Cell group"
# Remove outliers
if(remove.outliers==TRUE){
# Find outliers
# PC1
lower.limit <- quantile(x, 0.01) - (1.5*IQR(x))
upper.limit <- quantile(x, 0.99) + (1.5*IQR(x))
index.rm.x <- which(x < lower.limit | x > upper.limit)
# PC2
lower.limit <- quantile(y, 0.01) - (1.5*IQR(y))
upper.limit <- quantile(y, 0.99) + (1.5*IQR(y))
index.rm.y <- which(y < lower.limit | y > upper.limit)
# Merge
index.rm <- unique(c(index.rm.x, index.rm.y))
# Remove outliers
if(length(index.rm) != 0) {
data <- data[-index.rm, ]
x <- x[-index.rm]
y <- y[-index.rm]
z <- z[-index.rm]
}
# Track progress
print(paste(length(index.rm), " outliers removed", sep=""))
}
# Color scheme
if(is.null(cell.group.colors[1])) {
gg_color_hue <- function(n) {
hues = seq(15, 375, length = n + 1)
hcl(h = hues, l = 65, c = 100)[1:n]
}
n = length(levels(z))
cols = gg_color_hue(n)
} else {
cols <- cell.group.colors
}
# Plot
plot <- ggplot() +
geom_point(data, mapping=aes(x=x, y=y, fill=z), size=point.size, pch=21, alpha=point.alpha, stroke=point.stroke) +
scale_fill_manual(values=cols) +
labs(title=maintitle, x=xtitle, y=ytitle, fill=legendtitle) +
theme(panel.grid.major=element_blank(),
panel.grid.minor=element_blank(),
panel.background=element_blank(),
plot.title = element_text(size=12, hjust=0.5),
axis.line=element_line(colour = "black"),
axis.title=element_text(size=12),
axis.text.x=element_text(size=10, colour="black"),
axis.text.y=element_text(size=10, colour="black"),
legend.title=element_text(size=8),
legend.text=element_text(size=8),
legend.key=element_rect(fill="white")
) +
guides(fill = guide_legend(override.aes=list(size=2, alpha=point.alpha, stroke=point.stroke), ncol=ncol.legends))
} else if(length(pcs)==3){
# Definition
data <- as.data.frame(res.pca$ind$coord)
x <- data[,pcs[1]]
y <- data[,pcs[2]]
z <- data[,pcs[3]]
group <- df.pheno$pca.cell.group.label
maintitle <- ""
xtitle <- ""
ytitle <- ""
legendtitle <- "Cell group"
# Remove outliers
if(remove.outliers==TRUE){
# Find outliers
# PC1
lower.limit <- quantile(x, 0.01) - (1.5*IQR(x))
upper.limit <- quantile(x, 0.99) + (1.5*IQR(x))
index.rm.x <- which(x < lower.limit | x > upper.limit)
# PC2
lower.limit <- quantile(y, 0.01) - (1.5*IQR(y))
upper.limit <- quantile(y, 0.99) + (1.5*IQR(y))
index.rm.y <- which(y < lower.limit | y > upper.limit)
# PC3
lower.limit <- quantile(z, 0.01) - (1.5*IQR(z))
upper.limit <- quantile(z, 0.99) + (1.5*IQR(z))
index.rm.z <- which(z < lower.limit | z > upper.limit)
# Merge
index.rm <- unique(c(index.rm.x, index.rm.y, index.rm.z))
# Remove outliers
if(length(index.rm) != 0) {
data <- data[-index.rm, ]
x <- x[-index.rm]
y <- y[-index.rm]
z <- z[-index.rm]
group <- group[-index.rm]
}
# Track progress
print(paste(length(index.rm), " outliers removed", sep=""))
}
# Color scheme
if(is.null(cell.group.colors[1])) {
gg_color_hue <- function(n) {
hues = seq(15, 375, length = n + 1)
hcl(h = hues, l = 65, c = 100)[1:n]
}
n = length(levels(group))
cols = gg_color_hue(n)
} else {
cols <- cell.group.colors
}
# Report variance explained
print(paste("PC", pcs[1], " (", round(factoextra::get_eigenvalue(res.pca)[pcs[1],2], digits=2), "%)" ,sep=""))
print(paste("PC", pcs[2], " (", round(factoextra::get_eigenvalue(res.pca)[pcs[2],2], digits=2), "%)" ,sep=""))
print(paste("PC", pcs[3], " (", round(factoextra::get_eigenvalue(res.pca)[pcs[3],2], digits=2), "%)" ,sep=""))
# Plot
plot <- ggplot(data, aes(x=x, y=y, z=z, fill=group)) +
theme_void() +
axes_3D(color="grey75") +
stat_3D(size=point.size, pch=21, alpha=point.alpha, stroke=point.stroke) +
scale_fill_manual(values=cols) +
#theme(legend.title=element_text(size=8),
#legend.text=element_text(size=8),
#legend.key=element_rect(fill="white")
#) +
guides(fill = guide_legend(override.aes=list(size=2, alpha=point.alpha, stroke=point.stroke), ncol=ncol.legends))
}
}
# Retrieve eigenvalues
results.eigen <- as.data.frame(factoextra::get_eigenvalue(res.pca))
. <- data.frame("pc"=row.names(results.eigen))
results.eigen <- cbind.data.frame(., results.eigen)
results.eigen$pc <- gsub("Dim.", "", results.eigen$pc, fixed=TRUE)
results.eigen$pc <- as.numeric(results.eigen$pc)
# Non-linear dimension reduction
if(mode=="umap") {
# Subset first PCs
data <- as.data.frame(res.pca$ind$coord)
data.small <- data[,c(1:npc.umap)]
# Reduce dimension
# Non-linear
set.seed(seed.umap)
umap_out <- umap::umap(data.small)
# Scatterplot: Annotate by donor ID
# Definition
data <- as.data.frame(umap_out$layout)
x <- data[,1]
y <- data[,2]
z <- df.pheno$pca.cell.group.label
maintitle <- ""
xtitle <- "UMAP-1"
ytitle <- "UMAP-2"
legendtitle <- "Cell group"
# Color scheme
if(is.null(cell.group.colors[1])) {
gg_color_hue <- function(n) {
hues = seq(15, 375, length = n + 1)
hcl(h = hues, l = 65, c = 100)[1:n]
}
n = length(levels(group))
cols = gg_color_hue(n)
} else {
cols <- cell.group.colors
}
# Plot
plot <- ggplot() +
geom_point(data, mapping=aes(x=x, y=y, fill=z), size=1.5, pch=21, alpha=0.8, stroke=0.1) +
scale_fill_manual(values=cols) +
labs(title=maintitle, x=xtitle, y=ytitle, fill=legendtitle) +
theme(panel.grid.major=element_blank(),
panel.grid.minor=element_blank(),
panel.background=element_blank(),
plot.title = element_text(size=12, hjust=0.5),
axis.line=element_line(colour = "black"),
axis.title=element_text(size=12),
axis.text=element_text(size=10, colour="black"),
legend.title=element_text(size=8),
legend.text=element_text(size=8),
legend.key=element_rect(fill="white")
) +
guides(fill = guide_legend(override.aes=list(size=2, alpha=0.8, stroke=0.1), ncol=ncol.legends))
}
######################################################################
# Save to new slot
MarvelObject$PCA$Exp$RawData <- df
MarvelObject$PCA$Exp$Results <- res.pca
MarvelObject$PCA$Exp$Plot.Data <- data
MarvelObject$PCA$Exp$Plot <- plot
MarvelObject$PCA$Exp$EigenValues <- results.eigen
return(MarvelObject)
}
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.