1 files changed, 94 insertions, 0 deletions
diff --git a/R/endpoints.R b/R/endpoints.R
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+endpoints <- function(fit, pseudoDT50 = FALSE) {
+  # Calculate dissipation times DT50 and DT90 and, if necessary, formation
+  # fractions and SFORB eigenvalues from optimised parameters
+  ep <- list()
+  obs_vars <- fit$obs_vars
+  parms.all <- fit$parms.all
+  ep$distimes <- data.frame(DT50 = rep(NA, length(obs_vars)), 
+			    DT90 = rep(NA, length(obs_vars)), 
+    row.names = obs_vars)
+  ep$ff <- vector()
+  ep$SFORB <- vector()
+  for (obs_var in obs_vars) {
+    type = names(fit$mkinmod$map[[obs_var]])[1]  
+    if (type == "SFO") {
+      k_names = grep(paste("k", obs_var, sep="_"), names(parms.all), value=TRUE)
+      k_tot = sum(parms.all[k_names])
+      DT50 = log(2)/k_tot
+      DT90 = log(10)/k_tot
+      for (k_name in k_names)
+      {
+        ep$ff[[sub("k_", "", k_name)]] = parms.all[[k_name]] / k_tot
+      }
+    }
+    if (type == "FOMC") {
+      alpha = parms.all["alpha"]
+      beta = parms.all["beta"]
+      DT50 = beta * (2^(1/alpha) - 1)
+      DT90 = beta * (10^(1/alpha) - 1)
+    }
+    if (type == "DFOP") {
+      k1 = parms.all["k1"]
+      k2 = parms.all["k2"]
+      g = parms.all["g"]
+      f <- function(t, x) {
+        fraction <- g * exp( - k1 * t) + (1 - g) * exp( - k2 * t)
+        (fraction - (1 - x/100))^2
+      }
+      DTmax <- 1000
+      DT50.o <- optimize(f, c(0.001, DTmax), x=50)$minimum
+      DT50 = ifelse(DTmax - DT50.o < 0.1, NA, DT50.o)
+      DT90.o <- optimize(f, c(0.001, DTmax), x=90)$minimum
+      DT90 = ifelse(DTmax - DT90.o < 0.1, NA, DT90.o)
+    }
+    if (type == "HS") {
+      k1 = parms.all["k1"]
+      k2 = parms.all["k2"]
+      tb = parms.all["tb"]
+      DTx <- function(x) {
+        DTx.a <- (log(100/(100 - x)))/k1
+        DTx.b <- tb + (log(100/(100 - x)) - k1 * tb)/k2
+        if (DTx.a < tb) DTx <- DTx.a
+        else DTx <- DTx.b
+        return(DTx)
+      }
+      DT50 <- DTx(50)
+      DT90 <- DTx(90)
+    }
+    if (type == "SFORB") {
+      # FOCUS kinetics (2006), p. 60 f
+      k_out_names = grep(paste("k", obs_var, "free", sep="_"), names(parms.all), value=TRUE)
+      k_out_names = setdiff(k_out_names, paste("k", obs_var, "free", "bound", sep="_"))
+      k_1output = sum(parms.all[k_out_names])
+      k_12 = parms.all[paste("k", obs_var, "free", "bound", sep="_")]
+      k_21 = parms.all[paste("k", obs_var, "bound", "free", sep="_")]
+
+      sqrt_exp = sqrt(1/4 * (k_12 + k_21 + k_1output)^2 + k_12 * k_21 - (k_12 + k_1output) * k_21)
+      b1 = 0.5 * (k_12 + k_21 + k_1output) + sqrt_exp
+      b2 = 0.5 * (k_12 + k_21 + k_1output) - sqrt_exp
+
+      SFORB_fraction = function(t) {
+        ((k_12 + k_21 - b1)/(b2 - b1)) * exp(-b1 * t) +
+        ((k_12 + k_21 - b2)/(b1 - b2)) * exp(-b2 * t)
+      }
+      f_50 <- function(t) (SFORB_fraction(t) - 0.5)^2
+      max_DT <- 1000
+      DT50.o <- optimize(f_50, c(0.01, max_DT))$minimum
+      if (abs(DT50.o - max_DT) < 0.01) DT50 = NA else DT50 = DT50.o
+      f_90 <- function(t) (SFORB_fraction(t) - 0.1)^2
+      DT90.o <- optimize(f_90, c(0.01, max_DT))$minimum
+      if (abs(DT90.o - max_DT) < 0.01) DT90 = NA else DT90 = DT90.o
+
+      for (k_out_name in k_out_names)
+      {
+        ep$ff[[sub("k_", "", k_out_name)]] = parms.all[[k_out_name]] / k_1output
+      }
+
+      # Return the eigenvalues for comparison with DFOP rate constants
+      ep$SFORB[[paste(obs_var, "b1", sep="_")]] = b1
+      ep$SFORB[[paste(obs_var, "b2", sep="_")]] = b2
+    }
+    ep$distimes[obs_var, ] = c(DT50, DT90)
+  }
+  return(ep)
+}