Collect results from groups to one string - regex

Question

I want to parse weather html page for Openhab.
This is significant part of whole html:
<!-- Amount of Sun -->
<tr>
<td class="label_det">
<span class="sum">∑</span> <span class="unit">in u</span>
</td>
<td class="sunamount">
10.2
</td>
<td class="sunamount">
10.6
</td>
<td class="sunamount">
5.9
</td>
<td class="sunamount">
6.8
</td>
<td class="dgrey sunamount">
6.8
</td>
<td class="dgrey sunamount">
5.4
</td>
<td class="sunamount">
5
</td>
</tr>
I would like to collect all numbers into one string, I understand that it's, perhaps, not possible, but may be...
So something like this: '10.2 10.6 5.9 6.8 6.8 5.4 5'
Example of full html and my current regex is here: https://regex101.com/r/nrzPHU/1
Thanks in advice.

Answer 1

You need named capture groups. Named capture groups allow you to specify a given part in regex with a name to extract it later. A named capture group starts with (? then followed by the regex and ended with ).
<td class\=\".*?sunamount\">\s+(?<amount>\d+(\.\d+)?)\s+<\/td>
You would then be able to extract the amount by applying your regex to the input and picking the group named amount out of it.
Reading about OpenHab online I'm not sure they support named capture groups. So an alternative would be using the regex above to match all lines with amounts in the input. Then using a regex replace on that matched string. So something like...
Use this regex to get amounts:
<td class\=\".*?sunamount\">\s+\d+(\.\d+)?\s+<\/td>
Use this regex on the result of the regex above to replace the non amounts (and replace them with an empty string to delete them):
([\s]|<td class=".*?">|<\/td>)