A Python script that applies your markup and rounding rules to a supplier's price list and saves your own

Example result

python merge_sales.py --month 2026-10

2026-11-02 09:14:03 INFO  Folder: sales/2026-10, 9 files found
2026-11-02 09:14:03 INFO  shop-01.csv: 1,284 rows
2026-11-02 09:14:04 INFO  shop-02.xlsx: 967 rows
2026-11-02 09:14:04 WARN  shop-07.csv: 3 rows without a price skipped (lines 88, 412, 913)
2026-11-02 09:14:05 INFO  Done: 10,412 rows -> report-2026-10.xlsx (sheets "Sales" and "Totals")

[columns]
date = Date, Sale date, Day
product = Product, Item, Name
quantity = Qty, Quantity, Pcs
price = Price, Unit price

def read_shop_file(path: Path, columns: dict[str, list[str]]) -> pd.DataFrame:
    """Reads one shop's file and gives it the report's column names."""
    table = pd.read_excel(path) if path.suffix == ".xlsx" else pd.read_csv(path, encoding="utf-8-sig")
    renamed = {}
    for name, variants in columns.items():
        found = next((c for c in table.columns if c.strip() in variants), None)
        if found is None:
            raise ReportError(f"{path.name}: no column for '{name}' (looked for {', '.join(variants)})")
        renamed[found] = name
    table = table.rename(columns=renamed)[list(columns)]
    table["shop"] = path.stem
    return table

About this service

When a supplier sends a new price list every week, recalculating your own prices by hand means hours in Excel and mistakes in the formulas. This Python script reads the supplier's file and applies your rules: a markup in percent or a fixed amount, from Standard different markups by category, brand or price band, a minimum margin, a currency rate you enter, and rounding such as up to .99 or to the nearest 10. It saves a new price list with the columns you need, ready for your shop or for customers, and lists rows it could not price. The rules are yours; the script does the arithmetic and gives no pricing advice. You run it yourself on your computer, so check the first lists against a few prices you work out by hand.

What is included

• What you getA ZIP archive with the Python script, a README with step-by-step instructions and, from Standard, a settings file with your markups and rounding; the code is also shown on the order page.
• Your markup rulesPercent or fixed, by category, brand or price band
• Rounding you chooseUp to .99, to the nearest 10, or as you set
• Your columnsOnly the columns you need, in your order
• Problem rows listedRows with no price or an unknown category are reported
• Readable codeWith comments, easy to change a rule later

How it works

1. 1
   RulesYou send a sample of the supplier's file and your markup rules
2. 2
   CodeWe write the script and the guide to running it
3. 3
   Try itYou run it on the latest list and check a few prices by hand
4. 4
   ChangesYou ask for changes within your package and send any error message

What we need from you

20-30 rows of the supplier's price list as it comes (Excel or CSV), your markup rules written plainly (for example 35% on everything under 50, 25% above, at least 5 in margin), the rounding you want, the currency rate if prices must be converted and where it comes from, and the columns your price list should have. If you have several suppliers (Premium), a sample from each. Your system: Windows, macOS or Linux.

We will ask you:

• What does the supplier send?
• What are your markup rules?
• How should prices be rounded?
• What should your price list contain?

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