See Prices of a Currency in Hledger

You can use --infer-market-prices to infer from price of a currency from transactions made with @@.

For example, to see gold prices: hledger prices --infer-market-prices gold.

To see gold prices along with percentage and amount differences, run the following Python script:

import re
import subprocess
 
result = subprocess.run(
    ["hledger", "prices", "--infer-market-prices", "gold"],
    capture_output=True,
    text=True
)
lines = result.stdout.splitlines()
 
prices = []
for line in lines:
    if not line.startswith("P"):
        continue
    match = re.match(r"P\s+(\S+)\s+(\S+)\s+([\d,.]+)\s+(\S+)", line.strip())
    if not match:
        continue
    date, commodity, price, currency = match.groups()
    price = price.replace(",", "")
    prices.append((date.replace("-", "/"), float(price)))
 
prices.sort()
 
for i in range(1, len(prices)):
    date, price = prices[i]
    prev_date, prev_price = prices[i-1]
 
    price_diff = price - prev_price
    perc_diff = price_diff / prev_price
 
    sign = "+" if price_diff >= 0 else "-"
    print(f"{prev_date} - {date}:    {sign}{abs(perc_diff):.2%} ({sign}{abs(price_diff):.2f} IDR)")