Project: s41467-024-50913-w | Function: DPGEA (r)

system: You are an expert R programmer implementing algorithms from scientific papers.
Complete the masked function based on the algorithm description.
Follow R best practices and maintain consistent code style.
Return **only** the complete R function code.

user: Complete this R function:

**DESCRIPTION:** Implements Dynamic Pseudospatial Gene Expression Analysis to identify genes that correlate with cell type classifications along pseudospatial trajectories, using correlation analysis and expression-weighted scoring to classify genes as specific to populations or shared across multiple populations

**KEY TERMS:** {
  "DPGEA": "Dynamic Pseudospatial Gene Expression Analysis",
  "pseudotime": "pseudospatial trajectory ordering",
  "rcorr": "correlation calculation",
  "classification": "population-specific gene assignment"
}

**CONTEXT CODE:** #' DPGEA: differential pseudospatial gradient expression analysis
#'
#' @param cds a cds file where pseudotime has already been calculated
#' @param condition the column of "cds@clusters@listData that contains the condition names
#' @param threshold the p value threshold, default is 0.01
#' @param count_thres reduce the count matrix by selecting a min of counts (based on rowSums). Default is 0
#' @return A list of dataframes including correlations, p-values and the final classification
#' @import Seurat Hmisc monocle3
#' @export

DPGEA <- function(cds, condition, threshold = 0.01, count_thres = 0) {
  stop("Function implementation has been masked")
}


Complete the function implementation replacing "stop("Not implemented")".