R/edgeprob2.R

In ergMargins: Process Analysis for Exponential Random Graph Models

#' Function to compute edge probabilities from a converged ERGM.
#' this is largely a wrapper function to btergm::edge.prob.The only differnece is built in error
#' handling for curved ergm--the native edge.prob returns an error when used on curved ergms
#' Original authors of edgeprob are Philip Leifeld, imported from btergm package in R
#' @param model An ergm object.
#' @param verbose Determines whether to print updates as the function progresses. Appealing in large networks.
#' edge.prob2()

getformula<-function(x){x@formula}
setMethod("getformula", signature = className("btergm", "btergm"),
          definition = function(x) x@formula)

setMethod("getformula", signature = className("mtergm", "btergm"),
          definition = function(x) x@formula)

setMethod("getformula", signature = className("ergm", "ergm"),
          definition = function(x) x$formula)
setMethod("getformula", signature = className("mlergm", "mlergm"),
          definition = function(x) x$formula)


edge.prob2<-function (model, verbose = FALSE)
{
  if(class(model)%in%"btergm"){
    out<-btergm::edgeprob(model)
    return(out)
  }
  object<-model
  if (class(object) %in% c("ergm","mlergm")) {
    tergm <- FALSE
  } else if (class(object) %in% c("btergm", "mtergm")) {
    tergm <- TRUE
  } else {
    stop(paste("The edgeprob function is only applicable to ergm, btergm, and",
               "mtergm objects."))
  }

  ##check for duplicated names
  if(class(object)%in%c("ergm","mlergm")){
    if(any(duplicated(network::get.vertex.attribute(model$network,"vertex.names")))){

      size<-network::network.size(model$network)
      network::set.vertex.attribute(model$network,"vertex.names",1:size)
    }
  }


  l <- suppressWarnings(tergmprepare2(formula = getformula(object), offset = FALSE,
                    blockdiag = FALSE, verbose = FALSE))
  for (cv in 1:length(l$covnames)) {
    assign(l$covnames[cv], l[[l$covnames[cv]]])
  }
  assign("offsmat", l$offsmat)
  form <- stats::as.formula(l$form)
  covnames <- l$covnames[-1]

  if(class(object)%in%"mlergm"){
    coefs<-object$theta
  }else{
    coefs <- btergm::coef(object)
  }
  if(ergm::is.curved(object)){
    coefs<-ergm::ergm.eta(coefs,object$etamap)
  }



  if (verbose == TRUE) {
    message("Creating data frame with predictors...")
  }
  Y <- NULL
  dyads <- NULL
  for (i in 1:length(l$networks)) {
    mat <- as.matrix(l$networks[[i]])
    imat <- matrix(rep(1:nrow(mat), ncol(mat)), nrow = nrow(mat))
    if ((class(l$networks[[i]]) %in% "network" && network::is.bipartite(l$networks[[i]])) ||
        (class(l$networks[[i]]) %in% "matrix" && is.mat.onemode(l$networks[[i]]) ==
         FALSE)) {
      mn <- nrow(mat) + 1
      mx <- nrow(mat) + ncol(mat)
      jmat <- matrix(rep(mn:mx, nrow(mat)), nrow = nrow(mat),
                     byrow = TRUE)
    }else {
      jmat <- matrix(rep(1:ncol(mat), nrow(mat)), nrow = nrow(mat),
                     byrow = TRUE)
    }
    f <- stats::as.formula(paste(l$form, " + edgecov(imat) + edgecov(jmat)"))
    mpli <- ergm::ergmMPLE(f)
    Y <- c(Y, mpli$response)
    dyads <- rbind(dyads, cbind(mpli$predictor, i))
  }
  term.names <- colnames(dyads)[-(length(colnames(dyads)):(length(colnames(dyads)) -
                                                             2))]
  term.names <- c(term.names, "i", "j", "t")
  dyads <- data.frame(dyads)
  colnames(dyads) <- term.names
  dyads <- cbind(Y, dyads)
  colnames(dyads)[1] <- "tie"
  class(dyads[, length(colnames(dyads))]) <- "integer"
  class(dyads[, length(colnames(dyads)) - 1]) <- "integer"
  class(dyads[, length(colnames(dyads)) - 2]) <- "integer"
  if(class(object)%in%"mlergm"){
    cf<-object$theta
  }else{
    cf <- btergm::coef(object)
  }
  cf.length <- length(cf)
  cf <- cf[!cf %in% c(Inf, -Inf)]
  if (length(cf) != cf.length) {
    warning(paste("There are structural zeros or ones. For these dyads, the",
                  "predicted probabilities are not valid and must be manually replaced",
                  "by 0 or 1, respectively."))
  }
  cbcoef <- cbind(cf)
  chgstat <- dyads[, 2:(ncol(dyads) - 3)]
  ##handle decay term in curved ergms
  if("mlergm"%in%class(object)){
    class(object)<-"ergm"
  }
  if(class(object)%in%"mtergm"){

    if(ergm::is.curved(object@ergm)){
      curved.term<-vector(length=length(object$etamap$curved))
      for(i in 1:length(object$etamap$curved)){
        curved.term[i]<-object$etamap$curved[[i]]$from[2]
      }
     # cbcoef<-cbcoef[-c(curved.term)]
      cbcoef<-ergm::ergm.eta(cbcoef,object$etamap)
    }

  }else{
          if(ergm::is.curved(object)){
          curved.term<-vector(length=length(object$etamap$curved))
          for(i in 1:length(object$etamap$curved)){
          curved.term[i]<-object$etamap$curved[[i]]$from[2]
          }
         # cbcoef<-cbcoef[-c(curved.term)]
          cbcoef<-ergm::ergm.eta(cbcoef,object$etamap)

        }
      }
  lp <- apply(chgstat, 1, function(x) t(x) %*% cbcoef)
  result <- c(1/(1 + exp(-lp)))
  i.name <- numeric(nrow(dyads))
  j.name <- numeric(nrow(dyads))
  for (t in 1:length(l$networks)) {
    vnames.t <- colnames(l$networks[[t]][, ])
    dyads.t <- dyads[which(dyads$t == t), ]
    i.name.t <- vnames.t[dyads.t$i]
    j.name.t <- vnames.t[dyads.t$j]
    i.name[which(dyads$t == t)] <- i.name.t
    j.name[which(dyads$t == t)] <- j.name.t
  }
  dyads$i.name <- i.name
  dyads$j.name <- j.name
  dyads <- cbind(dyads, result)
  colnames(dyads)[ncol(dyads)] <- "probability"
  dyads <- dyads[order(dyads$t, dyads$i, dyads$j), ]
  rownames(dyads) <- NULL
  return(dyads)
}