Extracting Month and Year from a string with Python Regex

Question

I have a string from which I want to extract month name and year with Python regex. The string looks like the following-

x='januray valo na Feb 2017 valo Jan-2015 anj 1900 puch Janu Feb Jan Mar 15 MMMay-85 anF 15'

I code should return the following-

['Feb 2017', 'Jan-2015', 'Mar 15', 'May-85']

I have tried-

re.findall('[Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec]{3}[\s-]\d{2,4}', x)

But I the code picking up anF 15 as well, i.e. I am getting the following output-

['Feb 2017', 'Jan-2015', 'Mar 15', 'May-85', 'anF 15']

How can I stop the code from picking up wroong combinations like Jan|Feb?

Tim Biegeleisen · Accepted Answer · 2019-03-20 05:08:00Z

Use an alternation for the abbreviated month names. That is, use the following regex pattern:

(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[\s-]\d{2,4}

This says what you intend, namely to match one of 12 abbreviated month names, followed by a space/dash, then 2 or 4 digits.

x = 'januray valo na Feb 2017 valo Jan-2015 anj 1900 puch Janu Feb Jan Mar 15 MMMay-85 anF 15'

results = re.findall('(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[\s-]\d{2,4}', x)
print(results)

['Feb 2017', 'Jan-2015', 'Mar 15', 'May-85']

The problem with your current pattern is that it using a character class:

[Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec]{3}[\s-]\d{2,4}

This actually says to match three letters from the letters contained by the month names (plus pipe). Put another way, you are saying this:

[abceglnoprtuvyADFJMNOS|]{3}[\s-]\d{2,4}

Pranav C Balan · Accepted Answer · 2019-03-20 05:15:32Z

1

You are using character class here [Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec]{3}, which means any character from the character collection with repetition 3({3}). In order to fix it use a non-capturing group instead.

re.findall('(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)[\s-]\d{2,4}', x)

edited Mar 20, 2019 at 5:15

answered Mar 20, 2019 at 5:08

Pranav C Balan

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Comments

Ahmed · Accepted Answer · 2019-03-20 08:59:15Z

1

/[a-z]{3}.?\d{4}/gi

this will work check here

answered Mar 20, 2019 at 8:59

Ahmed

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