Implemented qtrunc.beta() (#54)

ocbe-uio · Jul 3, 2024 · af896aa · af896aa
1 parent 536ee4b
commit af896aa
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diff --git a/R/qtrunc.R b/R/qtrunc.R
@@ -33,6 +33,16 @@ qtrunc.generic <- function(p, ..., lower.tail, log.p) {
   UseMethod("qtrunc", p)
 }
 
+qtrunc.beta <- function(
+    p, shape1, shape2, a = 0, b = 1, ..., lower.tail, log.p
+  ) {
+  F_a <- pbeta(a, shape1, shape2, ncp = 0, lower.tail, FALSE)
+  F_b <- pbeta(b, shape1, shape2, ncp = 0, lower.tail, FALSE)
+  rescaled_p <- rescale_p(p, F_a, F_b, lower.tail, log.p)
+  q <- qbeta(rescaled_p, shape1, shape2, ncp = 0, lower.tail, FALSE)
+  return(q)
+}
+
 qtrunc.normal <- function(
     p, mean = 0, sd = 1, a = -Inf, b = Inf, ..., lower.tail, log.p
   ) {

diff --git a/tests/testthat/test-qtrunc-truncated-a.R b/tests/testthat/test-qtrunc-truncated-a.R
@@ -1,5 +1,33 @@
 context("qtrunc, lower truncation")
 
+test_that("qtrunc() works as expected (beta)", {
+  for (lg in c(FALSE, TRUE)) {
+    for (lt in c(TRUE, FALSE)) {
+      for (i in seq_len(3L)) {
+        shp1 <- sample(1:10, 1L)
+        shp2 <- sample(1:10, 1L)
+        pt <- runif(i)
+        if (lg) pt <- log(pt)
+        a <- qtrunc(min(pt) / 2, "beta", shp1, shp2, lower.tail = lt, log.p = lg)
+        q_trunc <- qtrunc(
+          pt, "beta", shp1, shp2, a = a, lower.tail = lt, log.p = lg
+        )
+        q_stats <- qbeta(pt, shp1, shp2, lower.tail = lt, log.p = lg)
+        expect_length(pt, i)
+        expect_length(q_trunc, i)
+        for (ii in seq_along(pt)) {
+          expect_gt(q_trunc[ii], q_stats[ii])
+          # Working back to p from q
+          ptr <- ptrunc(
+            q_trunc[ii], "beta", shp1, shp2, lower.tail = lt, log.p = lg, a = a
+          )
+          expect_equal(pt[ii], ptr)
+        }
+      }
+    }
+  }
+})
+
 test_that("qtrunc() works as expected (normal)", {
   for (lg in c(FALSE, TRUE)) {
     for (lt in c(TRUE, FALSE)) {

diff --git a/tests/testthat/test-qtrunc-truncated-ab.R b/tests/testthat/test-qtrunc-truncated-ab.R
@@ -1,5 +1,34 @@
 context("qtrunc, upper truncation")
 
+test_that("qtrunc() works as expected (beta)", {
+  for (lg in c(FALSE, TRUE)) {
+    for (lt in c(TRUE, FALSE)) {
+      for (i in seq_len(3L)) {
+        shp1 <- sample(1:10, 1L)
+        shp2 <- sample(1:10, 1L)
+        pt <- runif(i)
+        ab <- c(runif(100L), pt)
+        b <- qtrunc(max(pt), "beta", shp1, shp2, lower.tail = lt, log.p = FALSE)
+        a <- qtrunc(min(pt), "beta", shp1, shp2, lower.tail = lt, log.p = FALSE)
+        if (lg) pt <- log(pt)
+        q_trunc <- qtrunc(
+          pt, "beta", shp1, shp2, b = b, lower.tail = lt, log.p = lg
+        )
+        q_stats <- qbeta(pt, shp1, shp2, lower.tail = lt, log.p = lg)
+        expect_length(pt, i)
+        expect_length(q_trunc, i)
+        for (ii in seq_along(pt)) {
+          # Working back to p from q
+          ptr <- ptrunc(
+            q_trunc[ii], "beta", shp1, shp2, lower.tail = lt, log.p = lg, b = b
+          )
+          expect_equal(pt[ii], ptr)
+        }
+      }
+    }
+  }
+})
+
 test_that("qtrunc() works as expected (normal)", {
   for (lg in c(FALSE, TRUE)) {
     for (lt in c(TRUE, FALSE)) {

diff --git a/tests/testthat/test-qtrunc-truncated-b.R b/tests/testthat/test-qtrunc-truncated-b.R
@@ -1,5 +1,35 @@
 context("qtrunc, upper truncation")
 
+test_that("qtrunc() works as expected (beta)", {
+  for (lg in c(FALSE, TRUE)) {
+    for (lt in c(TRUE, FALSE)) {
+      for (i in seq_len(3L)) {
+        shp1 <- sample(1:10, 1L)
+        shp2 <- sample(1:10, 1L)
+        pt <- runif(i)
+        if (lg) pt <- log(pt)
+        b <- qtrunc(
+          max(runif(10L, pt)), "beta", shp1, shp2, lower.tail = lt, log.p = FALSE
+        )
+        q_trunc <- qtrunc(
+          pt, "beta", shp1, shp2, b = b, lower.tail = lt, log.p = lg
+        )
+        q_stats <- qbeta(pt, shp1, shp2, lower.tail = lt, log.p = lg)
+        expect_length(pt, i)
+        expect_length(q_trunc, i)
+        for (ii in seq_along(pt)) {
+          expect_lt(q_trunc[ii], q_stats[ii])
+          # Working back to p from q
+          ptr <- ptrunc(
+            q_trunc[ii], "beta", shp1, shp2, lower.tail = lt, log.p = lg, b = b
+          )
+          expect_equal(pt[ii], ptr)
+        }
+      }
+    }
+  }
+})
+
 test_that("qtrunc() works as expected (normal)", {
   for (lg in c(FALSE, TRUE)) {
     for (lt in c(TRUE, FALSE)) {

diff --git a/tests/testthat/test-qtrunc-untruncated.R b/tests/testthat/test-qtrunc-untruncated.R
@@ -1,5 +1,30 @@
 context("qtrunc, untruncated")
 
+test_that("qtrunc() works as expected (beta)", {
+  for (lg in c(FALSE, TRUE)) {
+    for (lt in c(TRUE, FALSE)) {
+      for (i in seq_len(3L)) {
+        shp1 <- sample(1:10, 1L)
+        shp2 <- sample(1:10, 1L)
+        pt <- runif(i)
+        if (lg) pt <- log(pt)
+        q_trunc <- qtrunc(pt, "beta", shp1, shp2, lower.tail = lt, log.p = lg)
+        q_stats <- qbeta(pt, shp1, shp2, lower.tail = lt, log.p = lg)
+        expect_length(pt, i)
+        expect_length(q_trunc, i)
+        for (ii in seq_along(pt)) {
+          expect_equal(q_trunc[ii], q_stats[ii])
+          # Working back to p from q
+          ptr <- ptrunc(
+            q_trunc[ii], "beta", shp1, shp2, lower.tail = lt, log.p = lg
+          )
+          expect_equal(pt[ii], ptr)
+        }
+      }
+    }
+  }
+})
+
 test_that("qtrunc() works as expected (normal)", {
   for (lg in c(FALSE, TRUE)) {
     for (lt in c(TRUE, FALSE)) {