From 49150338fd012dc2d8086b1a2bfc3c3f652d4b3a Mon Sep 17 00:00:00 2001
From: Castorp <50649074+ShinDongWoon@users.noreply.github.com>
Date: Sat, 16 Aug 2025 21:33:01 +0900
Subject: [PATCH] Allow default device selection without interaction

---
 LGHackerton/predict.py      |  3 +-
 LGHackerton/train.py        |  3 +-
 LGHackerton/utils/device.py | 64 ++++++++++++++++++++++++++-----------
 3 files changed, 50 insertions(+), 20 deletions(-)

diff --git a/LGHackerton/predict.py b/LGHackerton/predict.py
index 6ddb083..69cbda4 100644
--- a/LGHackerton/predict.py
+++ b/LGHackerton/predict.py
@@ -44,7 +44,8 @@ def convert_to_submission(pred_df: pd.DataFrame, sample_path: str) -> pd.DataFra
     return out_df
 
 def main():
-    device = select_device()
+    # Default to environment variable ``DEVICE`` or CPU without interactive input
+    device = select_device(os.environ.get("DEVICE", "cpu"))
 
     pp = Preprocessor(); pp.load(ARTIFACTS_PATH)
 
diff --git a/LGHackerton/train.py b/LGHackerton/train.py
index c960a52..6ced657 100644
--- a/LGHackerton/train.py
+++ b/LGHackerton/train.py
@@ -29,7 +29,8 @@ def _read_table(path: str) -> pd.DataFrame:
     raise ValueError("Unsupported file type. Use .csv or .xlsx")
 
 def main():
-    device = select_device()  # ask user for compute environment
+    # Default to environment variable ``DEVICE`` or CPU without interactive input
+    device = select_device(os.environ.get("DEVICE", "cpu"))
 
     df_train_raw = _read_table(TRAIN_PATH)
     pp = Preprocessor()
diff --git a/LGHackerton/utils/device.py b/LGHackerton/utils/device.py
index b6b5812..165bd1b 100644
--- a/LGHackerton/utils/device.py
+++ b/LGHackerton/utils/device.py
@@ -1,24 +1,52 @@
-import torch
+"""Utilities for selecting the computation device.
 
+This module tries to import :mod:`torch` but falls back to ``None`` if the
+library is not available.  Downstream code can therefore still run on
+environments where PyTorch is not installed (e.g. when only using the LightGBM
+model).
+"""
 
-def select_device() -> str:
-    """Interactively select computing device.
+from __future__ import annotations
 
-    Returns 'cpu', 'cuda', or 'mps'.
+import os
+
+try:  # pragma: no cover - best effort in absence of torch
+    import torch
+except Exception:  # torch is optional, treat as unavailable if import fails
+    torch = None
+
+
+def select_device(default: str | None = None) -> str:
+    """Select a computation device.
+
+    The function interacts with the user to select ``'cpu'``, ``'cuda'`` or
+    ``'mps'`` (Apple Metal) when no default is provided.  If a default device is
+    supplied via the ``default`` argument or the ``DEVICE`` environment
+    variable, that value is returned immediately without prompting.  When
+    running in a non-interactive environment where ``input`` raises
+    :class:`EOFError`, the ``default``/environment variable value is returned or
+    ``'cpu'`` if none was given.
     """
-    while True:
-        choice = input("Select compute environment (macOS/gpu/cpu): ").strip().lower()
-        if choice == "macos":
-            if torch.backends.mps.is_available():
-                return "mps"
-            else:
+
+    default_device = default or os.environ.get("DEVICE")
+    if default_device:
+        return default_device
+
+    try:
+        while True:
+            choice = input("Select compute environment (macOS/gpu/cpu): ").strip().lower()
+            if choice == "macos":
+                if torch and getattr(torch.backends, "mps", None) and torch.backends.mps.is_available():
+                    return "mps"
                 print("MPS not available. Please choose another option.")
-        elif choice in ("gpu", "cuda"):
-            if torch.cuda.is_available():
-                return "cuda"
-            else:
+            elif choice in ("gpu", "cuda"):
+                if torch and torch.cuda.is_available():
+                    return "cuda"
                 print("CUDA GPU not available. Please choose another option.")
-        elif choice == "cpu":
-            return "cpu"
-        else:
-            print("Invalid option. Choose from macOS/gpu/cpu.")
+            elif choice == "cpu":
+                return "cpu"
+            else:
+                print("Invalid option. Choose from macOS/gpu/cpu.")
+    except EOFError:
+        # When running without a TTY, return the safest option.
+        return "cpu"