带有范围结构的python中的正则表达式

Question

I need to fetch lower and upper values in a string having structure in a mix of the following formats:

Rules:
1. If lower and upper range is available then they are separated by '-'. 
2. Sometimes the range is written as <=xx.y

2a. If 'less than' is anywhere in the text then search for the number. pl. see Example below:

3. If at all age range appears then it appears always before the range, separated from range by a ':'
4. the unit is optional

Example data

10.0 - 35.0 MCG/ML
<=6.0 MG/24 H
51-60 YEARS: 37-129
15 - 60
0.5-9.9 %
LESS THAN 30 PG/ML
LESS THAN OR EQUAL 35 UG/DL
LESS THAN OR EQUAL TO 35
NEGATIVE: LESS THAN 20
REF RANGE LESS THAN 2.0
1.3 OR LESS PMOL/L
LAR: LESS THAN 1 NG/M

From the above, sample, my output would be:

10.0,35.0, MCG/ML
0, 6.0, MG/24 H
37, 129,
15,60
0.5, 9.9, %

Edit:

the string is in 'refVal'
re.search(r'([0-9]*\.?[0-9]*)\s*-\s*([0-9]*\.?[0-9]*)', refVal)
re.search(r'(<=|<|<\s*=|<\sOR\s=)\s*([0-9.]+)', refVal)

I added some more examples in the example above (especially for less than). I want to write Regex that fetch the value if 'Less Than' is in the text.

The following gives me unwanted 'None'.

>>> re.search(r'([0-9.]+) OR LESS|LESS THAN ([0-9.]+)', '5.4 OR LESS').groups()
('5.4', None)

Answer 1

IMO you aren't going to get a reliable solution with regex alone. If it were me, I'd break it down into multiple conditions and regexes. Having said that, for shits and grins I did come up with this...it does match for everything above, but it is quite ugly; for starters the data is captured to different groups depending on the format...

(?(?=.*:).*:\s*([0-9.]+)\s*-\s*([0-9.]+)|(?(?=.*\<=)(.*?)<=\s*([0-9.]+)\s*(.*)|([0-9.]+)\s*-\s*([0-9.]+)\s*(.*)))