Question: I have a number of strings similar to `Current Level: 13.4 db.` and I would like to extract just the floating point number. I say floating and not decimal as it's sometimes whole. Can RegEx do this or is there a better way?

Answer: 
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

```
I think that you'll find interesting stuff in the following answer of mine that I did for a previous similar question:

<https://stackoverflow.com/q/5929469/551449>

In this answer, I proposed a pattern that allows a regex to catch any kind of number and since I have nothing else to add to it, I think it is fairly complete