From a519043f1bdc9e71647d4daad55a072133b1be0d Mon Sep 17 00:00:00 2001
From: Ben Letham <bletham@gmail.com>
Date: Mon, 17 Aug 2020 16:24:34 -0700
Subject: [PATCH] Fix bug in changepoint handling in prophet_copy (#1529)

---
 R/R/diagnostics.R               | 3 ++-
 python/fbprophet/diagnostics.py | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/R/R/diagnostics.R b/R/R/diagnostics.R
index 709bb7c..242216d 100644
--- a/R/R/diagnostics.R
+++ b/R/R/diagnostics.R
@@ -181,7 +181,8 @@ prophet_copy <- function(m, cutoff = NULL) {
     changepoints <- m$changepoints
     if (!is.null(cutoff)) {
       cutoff <- set_date(cutoff)
-      changepoints <- changepoints[changepoints <= cutoff]
+      last_history_date <- max(m$history$ds[m$history$ds <= cutoff])
+      changepoints <- changepoints[changepoints < last_history_date]
     }
   } else {
     changepoints <- NULL
diff --git a/python/fbprophet/diagnostics.py b/python/fbprophet/diagnostics.py
index 5ca3159..b1d4f3f 100644
--- a/python/fbprophet/diagnostics.py
+++ b/python/fbprophet/diagnostics.py
@@ -268,8 +268,9 @@ def prophet_copy(m, cutoff=None):
     if m.specified_changepoints:
         changepoints = m.changepoints
         if cutoff is not None:
-            # Filter change points '<= cutoff'
-            changepoints = changepoints[changepoints <= cutoff]
+            # Filter change points '< cutoff'
+            last_history_date = max(m.history['ds'][m.history['ds'] <= cutoff])
+            changepoints = changepoints[changepoints < last_history_date]
     else:
         changepoints = None