If then logic

We often need to label rows based on rules. Is this a large transaction? Domestic or cross-border? Services or goods? This kind of conditional logic is the foundation of categorization, risk assessment, and decision-making.

In this section, you'll learn how to apply "if... then..." rules using Python — just like you would in Excel's IF() function.

Add a simple condition column

Excel

In Excel, you use =IF(A2>10000000, "Large", "Small") to label rows based on a condition.

t0 Prompt

Label each transaction as "Large" or "Small"

Add a column that says "Yes" if over 10 million

Code

The python code looks as follows:

transactions["Amount"] = pd.to_numeric(transactions["Amount"])
transactions["Size"] = np.where(transactions["Amount"] > 10_000_000, "Large", "Small")
transactions

Add multiple conditional outcomes

Excel

In Excel, you might nest IF() statements: =IF(A2>10M,"Large",IF(A2>5M,"Medium","Small")).

t0 Prompt

Label transactions as large, medium, or small

Add tiers based on amount

Use multiple thresholds in column Amount: X, Y, and Z

Code

The python code looks as follows:

transactions["Amount"] = pd.to_numeric(transactions["Amount"])
def classify(x):
    if x > 10_000_000:
        return "Large"
    elif x > 5_000_000:
        return "Medium"
    else:
        return "Small"
transactions["Category"] = transactions["Amount"].apply(classify)
transactions

Add logic based on multiple columns

Excel

In Excel, you'd write something like =IF(AND(A2="Italy",B2="Brazil"),"Cross-border","Domestic").

t0 Prompt

Flag rows where seller and buyer are in different countries

Add column for "Cross-border" or "Domestic"

Code

The python code looks as follows:

transactions["Border"] = np.where(
    transactions["Seller Country"] != transactions["Buyer Country"],
    "Cross-border",
    "Domestic"
)
transactions