I have a string, which can contain 10 or more characters ([0-9a-zA-Z]), e.g.: abcdefghij12345

I want to catch following characters in groups:

• Group 1: Character position "1 and 2": ab
• Group 2: Character position "3 and 4": cd
• Group 3: Character position "5 - 10": efghij
• Group 4: Character position "6 - Last position of string": fghij12345

Group 1-3 works, but how can a get postion "6 - last postion of string" in Group 4?

What I already have?

r'^([0-9a-zA-Z]{2})([0-9a-zA-Z]{2})([0-9a-zA-Z]{6})'

I expect to get all four groups with one Regex expression. How to expand my expression to get additionally group 4?

CodePudding user response：

You could use a positive lookahead:

^([\da-zA-Z]{2})([\da-zA-Z]{2})(?=([\da-zA-Z]{6})).([\da-zA-Z].*)$

• ^ - start of line anchor
• ([\da-zA-Z]{2}) - first capture group, pos 1-2
• ([\da-zA-Z]{2}) - second capture group, pos 3-4
• (?=([\da-zA-Z]{6})) - positive lookahead, third capture, pos 5-10
• .([\da-zA-Z].*) - discard one character and capture the rest as forth capture, pos 6-end
• $ - end of line anchor

Demo

CodePudding user response：

Since it's an index/position issue, why not just using classical slicing with a tuple-comp ?

S = "abcdefghij12345"

g1, g2, g3, g4 = (S[i:j] for i, j in [(0, 2), (2, 4), (4, 10), (5, None)])

Output :

ab          # <- group1 
cd          # <- group2
efghij      # <- group3
fghij12345  # <- group4