python match string in line with regex and get a certain value

Question

I have the following which is part of a line in a log file

-FDH-11 TIP: - 146/S Q: 48

which I want to match with regex . Is there a way to get the value of Q in the above input. I am not sure the length between -FDH- and Q: is always the same. So ideally if I found -FDH- and Q: then get the value of Q.

There can be more Q's between FDH or not? Would be ok to look just for the FDH and then for the Q? — fernand0
– fernand0, Commented Dec 1, 2017 at 17:40
@fernand0 No other Q in line and yes for the second part of your question. Thanks guys!! — Gakis41
– Gakis41, Commented Dec 1, 2017 at 17:46
@Gakis41 if there are no other instances of Q: in the string, the solution below provided by user3354059 should work for you. — ctwheels
– ctwheels, Commented Dec 1, 2017 at 17:47

ctwheels · Accepted Answer · 2017-12-01 17:53:16Z

3

Code

See regex in use here

-FDH-.*?\bQ:\s*(\S+)

Explanation

-FDH- Match this literally
.*? Match any character any number of times, but as few as possible
\b Assert position as a word boundary
Q: Match this literally
\s* Match any number of whitespace characters
(\S+) Capture one or more non-whitespace characters into capture group 1

answered Dec 1, 2017 at 17:53

ctwheels

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Comments

user3354059 · Accepted Answer · 2017-12-01 17:41:27Z

0

You probably don't need to use regex for this. If there is only one instance of "Q:" in the string, then you can just split on that and get the value after with the following:

str = "-FDH-11 TIP: - 146/S Q: 48"
parts = str.split("Q: ")
q_value = parts[1]

answered Dec 1, 2017 at 17:41

user3354059

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3 Comments

ctwheels Over a year ago

What if there's another variable with a Q in it like GQ:? The user also specified that it should be after -FDH-, which might imply that other instances exist where Q might be found. I do agree, however, that the OP should present us with more information about the string.

user3354059 Over a year ago

Then it wouldn't work which is why I said there can only be one instance of "Q:", but I was just trying to present the simplest and easiest to implement possible answer based on the above input. It won't work if your example occurs.

Gakis41 Over a year ago

@ctwheels Q should be alone with a ":" in front.

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