Ratios Between Gold, Platinum and Silver

Ratios between Gold, Platinum and Silver show clear trends. Gold/Silver ratio shows big fluctuations. Platinum/Silver ratio shows a clear downward trend.

    import yfinance as yf
import matplotlib.pyplot as plt
import pandas as pd

dateStart = "2015-01-01"
dateEnd   = "2025-12-31"

tickers = ["GC=F", "SI=F", "PL=F"]  # Gold, Silver, Platinum futures

# yfinanceからまとめて取得（警告回避のため auto_adjust を明示）
df = yf.download(
    tickers,
    start=dateStart,
    end=dateEnd,
    auto_adjust=False,   # True/FalseどちらでもOK。とにかく明示する
    progress=False
)

# dfは MultiIndex columns になりやすい：['Close'] で3銘柄の終値DataFrameが取れる
close = df["Close"].copy()

# 月次平均（pandas警告対応：'M' -> 'ME'）
close_m = close.resample("ME").mean()

# 比率をDataFrameで計算（列名で参照）
ratio = pd.DataFrame({
    "Gold/Silver": close_m["GC=F"] / close_m["SI=F"],
    "Gold/Platinum": close_m["GC=F"] / close_m["PL=F"],
    "Platinum/Silver": close_m["PL=F"] / close_m["SI=F"],
}).dropna()

ax = ratio.plot(figsize=(12, 6))
ax.set_title("Monthly Price Ratios (Futures via Yahoo Finance)")
ax.set_xlabel("Month")
ax.set_ylabel("Ratio")
plt.show()