From 96f2bd186ac0854ed9f5b9c9d4d76848cb71af1d Mon Sep 17 00:00:00 2001
From: Frits Hermans <post@fritshermans.nl>
Date: Fri, 5 Dec 2025 11:30:50 +0100
Subject: [PATCH] add warning about perfectly correlated columns

---
 phik/bivariate.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/phik/bivariate.py b/phik/bivariate.py
index cb7f396..28a48b7 100644
--- a/phik/bivariate.py
+++ b/phik/bivariate.py
@@ -276,7 +276,10 @@ def phik_from_chi2(
     elif chi2 >= chi2_max:
         return 1.0
 
-    rho = optimize.brentq(
-        chi2_from_phik, 0, 1, args=(n, chi2, corr0, scale, sx, sy, pedestal), xtol=1e-5
-    )
+    try:
+        rho = optimize.brentq(
+            chi2_from_phik, 0, 1, args=(n, chi2, corr0, scale, sx, sy, pedestal), xtol=1e-5
+        )
+    except ValueError as e:
+            raise ValueError(f"{str(e)}. Your data might contain columns with perfect correlation")
     return rho