How to extract string information from these two strings?

Question

I want to write a single regular expression code to extract the string from these two strings:

string1 = '@HISEQ:625:HC2T5BCXY:1:1101:1177:2101'
string2 = '@SRR7216015.1 HISEQ:630:HC2VKBCXY:1:1101:1177:2073/1'

I want to extract the string right after the @ until it hit the end or a space to get

HISEQ:625:HC2T5BCXY:1:1101:1177:2101 from string1

or

SRR7216015.1 from string2

So, how to do it. I've tested a bunch of the regular expression code but couldn't do it.

Below is the code I tried:

string1 = '@HISEQ:625:HC2T5BCXY:1:1101:1177:2101'
string2 = '@SRR7216015.1 HISEQ:630:HC2VKBCXY:1:1101:1177:2073/1'
pattern1 = re.compile(r'@(\w*.*:*\d*:*\w*:*\d*:*\d*[$|\s])')
print(pattern1.search(string1).group(1))

Thanks in advance!

Answer 1

Just use

@(\S+)

and take the first group. Lookarounds or alternations - as suggested in other answers - are expensive.

Answer 2

You could use this regex for that:

(?<=@).*?(?= |$)

Use lookarounds. (?<=@) checks for an @ signt before, (?= |$) matches an spaces or end of string. .* mathes everything between

https://regex101.com/r/p7kI2O/1