Pythonコードを保存するPythonコード

# Program Name: create_and_download_pyfile.ipynb
# Creation Date: 20251015
# Overview: Create a Python file (.py) in Google Colab and download it automatically
# Usage: Run in Google Colab → generates collision_vpython.py and downloads it

from google.colab import files

# ==== 保存したいPythonコード / Python code content ====
code = """# Program Name: collision_vpython.py
# Creation Date: 20251015
# Overview: Simulate 1D elastic collision between two balls using VPython
# Usage: Run in VS Code terminal → python collision_vpython.py

from vpython import sphere, vector, rate, color, scene

m1, m2 = 2.0, 1.0
v1, v2 = 2.0, -1.0
r1, r2 = 0.5, 0.5
dt = 0.005
x1_init, x2_init = -4.0, 4.0

scene.background = color.white
scene.width = 800
scene.height = 400
scene.center = vector(0, 0, 0)
scene.title = "1D Elastic Collision Simulation"

ball1 = sphere(pos=vector(x1_init, 0, 0), radius=r1, color=color.blue, make_trail=True)
ball2 = sphere(pos=vector(x2_init, 0, 0), radius=r2, color=color.red, make_trail=True)

v1_vec = vector(v1, 0, 0)
v2_vec = vector(v2, 0, 0)

while True:
    rate(200)
    ball1.pos += v1_vec * dt
    ball2.pos += v2_vec * dt

    if abs(ball1.pos.x - ball2.pos.x) <= (r1 + r2):
        v1_new = ((m1 - m2) / (m1 + m2)) * v1_vec.x + (2 * m2 / (m1 + m2)) * v2_vec.x
        v2_new = ((2 * m1) / (m1 + m2)) * v1_vec.x + ((m2 - m1) / (m1 + m2)) * v2_vec.x
        v1_vec.x, v2_vec.x = v1_new, v2_new

    if abs(ball1.pos.x) > 6:
        v1_vec.x *= -1
    if abs(ball2.pos.x) > 6:
        v2_vec.x *= -1
"""

# ==== ファイル作成 / Write file ====
filename = "collision_vpython.py"
with open(filename, "w", encoding="utf-8") as f:
    f.write(code)

# ==== ダウンロード実行 / Download file ====
files.download(filename)

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使い方

1. 上記を save_python_file.py などの名前で保存。

2. 実行：

   python save_python_file.py
   

3. 同じフォルダに collision_vpython.py が生成されます。

4. その中身を変更したい場合は、code = """ ... """ の中に任意のPythonコードを書けばOKです。