Extract float surrounded by white spaces within string

I have strings similar to this example:

str = '     area                                AMW1  =     93.3 m2 ';

And I would like to only extract the floating point number (possibly with sign "-") 93.3. The float I like to extract is always surrouned by white spaces.

How can I do that?

I tried

s = regexp(str,'\d+\.?\d*','match')

However, it matches also the 1 and the 2. Various other expressions I found do not work neither...

Thank you.

Solution

You can use

regexp(str,'-?\d+\.\d+','match')

Or, if you need to also match a +:

regexp(str,'[-+]?\d+\.\d+','match')

If you need to match within whitespace boundaries only:

regexp(str,'(?<!\S)[-+]?\d+\.\d+(?!\S)','match')

If the float value must be in between two whitespace chars:

regexp(str,'(?<=\s)[-+]?\d+\.\d+(?=\s)','match')

Details

(?<=\s) - right before the match, there must be a whitespace
(?<!\S) - right before the match, there must be start of string, or a whitespace
[-+]? - an optional + or -
\d+ - one or more digits
\. - a dot
\d+ - one or more digits
(?!\S) - right after, there must be the end of string or a whitespace
(?=\s) - right after the match, there must be a whitespace.

And if you need to find both integer or floats, replace \d+\.\d+ with \d+(?:\.\d+)?.