How Can I Extract Floating-Point Numbers from a String Using Regular Expressions in Python?

Extracting Floating-Point Numbers from a String Using Regular Expressions

In programming, it's often necessary to extract data from text strings. In this case, you're seeking to extract floating-point numbers from a string like "Current Level: 13.4 db."

Regular Expression Solution

Using regular expressions, you can define a pattern that captures floating-point numbers. Consider the following Python code:

import re

string = "Current Level: 13.4db."
result = re.findall(r"\d+\.\d+", string)
print(result)

This code uses the regular expression pattern d .d :

• d : Matches one or more digits, representing the whole number part of the float.
• .: Matches the decimal point.
• d : Matches one or more digits after the decimal point, representing the fractional part of the float.

The result list will contain the extracted floating-point number: ['13.4'].

Robust Solution with Validation

For a more robust approach, use the pattern r"[- ]?(?:d*.*d )". This pattern handles both positive and negative signs, as well as optional digits before the decimal point.

result = re.findall(r"[-+]?(?:\d*\.*\d+)", string)
print(result)

In addition to extraction, you can validate user input by attempting to convert it to a float directly:

user_input = "Current Level: 1e100 db"
for token in user_input.split():
    try:
        float_value = float(token)
        print(f"{float_value} is a float")
    except ValueError:
        print(f"{token} is something else")

This code iterates over the tokens in the input string and attempts to convert them to floats. If a conversion succeeds, the token is a float. Otherwise, it's considered something else.

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