Python regex extraction

Question

I have a string called "strtosearch2" like this:

[02112017 072755 332][1][ERROR]> ----Message : IDC_NO_MEDIA
[02112017 072755 332][1][INFO]> ----              
[02112017 104502 724][1][ERROR]> ----Message : DEV_NOT_READY
[02112017 104502 724][1][INFO]> ----              
[02112017 104503 331][1][ERROR]> ----Message : DEV_NOT_READY
[02112017 104503 331][1][INFO]> ----

I want to extract the dates which are having the lines "ERROR" only. I wrote my regex as follows:

down2Date= re.findall(r'\[(.*?)\s\d{6}\s\d{3}\]\[\d\]\[ERROR\]',strtosearch2,re.DOTALL)

output as follows:

02112017
02112017 072755 332][1][INFO]> ----              
[02112017
02112017 104502 724][1][INFO]> ----              
[02112017

My target output:

02112017
02112017
02112017

How can I fix this ?. Thank you

suggestion: sometimes you don't need to define exact input pattern.. for given sample, re.findall(r'(?m)^\[(\d+).*ERROR', strtosearch2) would work too.. if not, try to add relevant sample when asking :) — Sundeep
– Sundeep, Commented Feb 28, 2018 at 8:14

Wiktor Stribiżew · Accepted Answer · 2018-02-28 07:24:24Z

2

You may anchor the pattern at the start of the line/string and remove the re.DOTALL modifier:

re.findall(r'(?m)^\[(.*?)\s\d{6}\s\d{3}]\[\d]\[ERROR]', s)

See the regex demo

With re.DOTALL, the . matched any char including line break chars.

With (?m), ^ matches the start of each line, not only the start of the whole string.

Also, \s can match line break chars, so you might want to use [^\S\r\n] instead of it to only match horizontal whitespace.

answered Feb 28, 2018 at 7:24

Wiktor Stribiżew

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Comments

Denis Rasulev · Accepted Answer · 2018-02-28 07:22:45Z

0

Try this:

down2Date = re.findall(r'^\[\d+\s\d+\s\d+\]\[\d\]\[ERROR\]', strtosearch2)

answered Feb 28, 2018 at 7:22

Denis Rasulev

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3 Comments

Sanket Over a year ago

can anyone specify what does this re.DOTALL had affected?

Wiktor Stribiżew Over a year ago

@Sanket See my answer.

Denis Rasulev Over a year ago

If the DOTALL flag has been specified, this matches any character including a newline. Details here

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