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 3. Various other expressions I found do not work neither...

Thank you.

CodePudding user response：

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 )?.

CodePudding user response：

try this:

re.compile(r'(?<=\s)\d (\.\d )?(?=\s)')