From af6038b8795c1b61c7aa060afbad5badf1e7a090 Mon Sep 17 00:00:00 2001
From: Daisuke Oyama <oyama@e.u-tokyo.ac.jp>
Date: Sun, 5 Jan 2025 16:01:49 +0900
Subject: [PATCH] Add `to_gam`

---
 quantecon/game_theory/__init__.py              |  2 +-
 quantecon/game_theory/game_converters.py       | 18 ++++++++++++++++++
 .../game_theory/tests/test_game_converters.py  | 18 ++++++++++++++++--
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/quantecon/game_theory/__init__.py b/quantecon/game_theory/__init__.py
index 4bcfe0a6..7ca07de5 100644
--- a/quantecon/game_theory/__init__.py
+++ b/quantecon/game_theory/__init__.py
@@ -24,4 +24,4 @@
 from .logitdyn import LogitDynamics
 from .polymatrix_game import PolymatrixGame
 from .howson_lcp import polym_lcp_solver
-from .game_converters import GAMReader, GAMWriter, from_gam
+from .game_converters import GAMReader, GAMWriter, from_gam, to_gam
diff --git a/quantecon/game_theory/game_converters.py b/quantecon/game_theory/game_converters.py
index 5bfeba4b..c5b305a5 100644
--- a/quantecon/game_theory/game_converters.py
+++ b/quantecon/game_theory/game_converters.py
@@ -226,3 +226,21 @@ def from_gam(filename: str) -> NormalFormGame:
 
     """
     return GAMReader.from_file(filename)
+
+
+def to_gam(g, file_path=None):
+    """
+    Write a NormalFormGame to a file in gam format.
+
+    Parameters
+    ----------
+    g : NormalFormGame
+
+    file_path : str, optional(default=None)
+        Path to the file to write to. If None, the result is returned as
+        a string.
+
+    """
+    if file_path is None:
+        return GAMWriter.to_string(g)
+    return GAMWriter.to_file(g, file_path)
diff --git a/quantecon/game_theory/tests/test_game_converters.py b/quantecon/game_theory/tests/test_game_converters.py
index 5e592569..719fcd5d 100644
--- a/quantecon/game_theory/tests/test_game_converters.py
+++ b/quantecon/game_theory/tests/test_game_converters.py
@@ -5,10 +5,10 @@
 import os
 from tempfile import NamedTemporaryFile
 from numpy.testing import assert_string_equal
-from quantecon.game_theory import NormalFormGame, GAMWriter
+from quantecon.game_theory import NormalFormGame, GAMWriter, to_gam
 
 
-class TestGAMWrite:
+class TestGAMWriter:
     def setup_method(self):
         nums_actions = (2, 2, 2)
         g = NormalFormGame(nums_actions)
@@ -45,3 +45,17 @@ def test_to_string(self):
         s_actual = GAMWriter.to_string(self.g)
 
         assert_string_equal(s_actual, self.s_desired)
+
+    def test_to_gam(self):
+        s_actual = to_gam(self.g)
+        assert_string_equal(s_actual, self.s_desired)
+
+        with NamedTemporaryFile(delete=False) as tmp_file:
+            temp_path = tmp_file.name
+            to_gam(self.g, temp_path)
+
+        with open(temp_path, 'r') as f:
+            s_actual = f.read()
+        assert_string_equal(s_actual, self.s_desired + '\n')
+
+        os.remove(temp_path)