From 67409a9fc404abc114720e8afb1a552c973a0d4e Mon Sep 17 00:00:00 2001
From: Sarah Teichman <teichs@uw.edu>
Date: Wed, 31 Jul 2024 16:06:57 -0700
Subject: [PATCH] use grant's more general way to check for an intercept column

---
 R/multinom_test.R | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/R/multinom_test.R b/R/multinom_test.R
index 4de5ca1..d00d704 100644
--- a/R/multinom_test.R
+++ b/R/multinom_test.R
@@ -30,8 +30,8 @@ covariates in formula must be provided.")
     X <- model.matrix(formula, data)
   }
   
-  # if X has intercept column, remove it 
-  if (sum(X[, 1] == 1) == nrow(X)) {
+  # if X has intercept column (or a column of repeating values), remove it 
+  if (all(round((X %*% solve(t(X) %*% X) %*% t(X)) %*% rep(1, nrow(X)), 1e-20) == 1)) {
     X <- X[, -1, drop = FALSE]
   }