How to Extract a Floating Number from a String

How to extract a floating number from a string

If your float is always expressed in decimal notation something like

>>> import re
>>> re.findall("\d+\.\d+", "Current Level: 13.4db.")
['13.4']

may suffice.

A more robust version would be:

>>> re.findall(r"[-+]?(?:\d*\.\d+|\d+)", "Current Level: -13.2db or 14.2 or 3")
['-13.2', '14.2', '3']

If you want to validate user input, you could alternatively also check for a float by stepping to it directly:

user_input = "Current Level: 1e100 db"
for token in user_input.split():
    try:
        # if this succeeds, you have your (first) float
        print float(token), "is a float"
    except ValueError:
        print token, "is something else"

# => Would print ...
#
# Current is something else
# Level: is something else
# 1e+100 is a float
# db is something else

How can I extract a floating point number from a string efficiently?

Use this:

        float number = Float.parseFloat(s.replaceAll("[^\\d.]", ""));
        System.out.println(number);

Or, what's already mentioned in the comments:
Get the substring which only contains the number. Then you can parse it to your data type.

        String s = "0.0234000ETH";
        String part1 = s.substring(0,8);
        float value = Float.parseFloat(part1);
        System.out.println(value);

Extracting floating number from string

You can add . in your Regex:

var t = '1,234.04 km';
var a = t.replace(/[^0-9.]/g, '') // 1234.04

parseFloat(a) // 1234.04

Python: Extract multiple float numbers from string

You could also use regex to do this

import re
s = "38.00,SALE ,15.20"
p = re.compile(r'\d+\.\d+')  # Compile a pattern to capture float values
floats = [float(i) for i in p.findall(s)]  # Convert strings to float
print floats

Output:

[38.0, 15.2]

how to extract floating numbers from strings in javascript

You can use the regex /[+-]?\d+(\.\d+)?/g in conjunction with String.match() to parse the numbers and Array.map() to turn them into floats:

var regex = /[+-]?\d+(\.\d+)?/g;

var str = '<tag value="20.434" value1="-12.334" />';
var floats = str.match(regex).map(function(v) { return parseFloat(v); });
console.log(floats);

var str2 = '20.434 -12.334';
var floats2 = str2.match(regex).map(function(v) { return parseFloat(v); });
console.log(floats2);

var strWithInt = "200px";
var ints = strWithInt.match(regex).map(function(v) { return parseFloat(v); });
console.log(ints);

See demo code here.