如何用Python正则表达式提取文本中2至2,000,000,000的美元金额？

Got it, let's tackle this regex problem for you. First, let's figure out why your original regex ^\{USD}?(\d*(\d\.?|\.\d{1,2}))$ wasn't working:

• It uses ^ and $ which match the start/end of an entire line, but your amounts are embedded in larger text.
• \{USD} tries to match literal curly brackets around "USD", which isn't present in your examples.
• It doesn't account for the "US" prefix, thousand separators (commas), or the required amount range.

Step 1: Build a Regex to Match US/USD + Amount Format #

First, let's create a regex that correctly identifies "US" or "USD" followed by a numeric amount (with optional commas and 1-2 decimal places):

\b(US(?:D)?)\s+([\d,]+(?:\.\d{1,2})?)

Let's break this down:

• \b: Word boundary to avoid matching partial words like "USDA" or "USX".
• (US(?:D)?): Captures either "US" or "USD" (the (?:D)? is a non-capturing group for the optional "D").
• \s+: Matches one or more spaces between the prefix and amount (adjust to \s* if there might be no space, e.g., "USD1234").
• ([\d,]+(?:\.\d{1,2})?): Captures the numeric amount:
  • [\d,]+: Matches digits with optional thousand separators.
  • (?:\.\d{1,2})?: Optional decimal part with 1-2 digits (non-capturing group to keep the clean match).

Step 2: Filter by Amount Range (2 to 2,240,000,000) #

Regex isn't great for complex numeric range checks—it gets messy fast. Instead, extract the matches first, then convert them to numbers to validate the range.

Here's a Python example to put it all together:

import re

# Sample input text
input_text = """
Here are some amounts to check:
USD 2,00
US 2,300,000
USD 1.99 (too low)
US 2240000000 (max valid)
USD 2250000000 (too high)
US 500.50
"""

# Our regex pattern
amount_pattern = r'\b(US(?:D)?)\s+([\d,]+(?:\.\d{1,2})?)'

# Extract all potential matches
raw_matches = re.findall(amount_pattern, input_text)

# Process and filter valid amounts
valid_amounts = []
for prefix, amount_str in raw_matches:
    # Remove commas and convert to float
    clean_amount = float(amount_str.replace(',', ''))
    # Check if within the valid range
    if 2 <= clean_amount <= 2240000000:
        # Reconstruct the original formatted string
        valid_amounts.append(f"{prefix} {amount_str}")

print("Valid extracted amounts:")
for item in valid_amounts:
    print(f"- {item}")

Output:

Valid extracted amounts:
- USD 2,00
- US 2,300,000
- US 2240000000
- US 500.50

Notes: #

• This handles odd formats like "USD 2,00" (even though the comma placement looks off—if that's a typo, you could add extra logic to clean up invalid comma positions, but the regex will still capture it).
• If your text has amounts with no spaces (e.g., "USD123,456"), just change \s+ to \s* in the regex to allow zero or more spaces.

内容的提问来源于stack exchange，提问作者Vanj