Number Trouble with Regex in Python

Question

I'm trying to filter a date retrieved from a .csv file, but no combination I try seems to work. The date comes in as "2011-10-01 19:25:01" or "year-month-date hour:min:sec".

I want just the year, month and date but I get can't seem to get ride of the time from the string:

date = bug[2] # Column in which the date is located  
date = date.replace('\"','') #getting rid of the quotations  
mdate = date.replace(':','')  
re.split('$[\d]+',mdate) # trying to get rid of the trailing set of number (from the time)

Thanks in advance for the advice.

JMax · Accepted Answer · 2012-01-13 07:46:35Z

8

If your source is a string, you'd probably better use strptime

import datetime
string = "2011-10-01 19:25:01"
dt = datetime.datetime.strptime(string, "%Y-%m-%d %H:%M:%S")

After that, use

dt.year
dt.month
dt.day

to access the data you want.

edited Jan 13, 2012 at 7:46

answered Jan 12, 2012 at 15:13

JMax

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5 Comments

Kevin Over a year ago

good idea, but I think the last line should be dt = datetime.datetime.strptime(string, "%Y-%m-%d %H:%M:%S")

JMax Over a year ago

@Kevin: Thanks. I've corrected my code I've written too quickly

Shahab Over a year ago

@JMax, it returns a ValueError: time data ' 2011-10-12 03:09:26' does not match format ...(the one in your code). Also thanks for the help

JMax Over a year ago

@Shahab: weird! I've tested the code in py-ide-online.appspot.com and it seems to work. Check you didn't add an extra space at the begining of your string (it exists in your comment)

Shahab Over a year ago

There are quotations in the retrieved date so I removed them with the replace code above, but I see what your saying and am trying to see where I went wrong----> i got it to work!

Marcin · Accepted Answer · 2012-01-12 15:11:49Z

6

Use datetime to parse your input as a datetime object, then output it in whatever format you like: http://docs.python.org/library/datetime.html

answered Jan 12, 2012 at 15:11

Marcin

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Comments

bkzland · Accepted Answer · 2012-01-12 15:13:54Z

1

I think you're confusing the circumflex for start of line and dollar for end of line. Try ^[\d-]+.

answered Jan 12, 2012 at 15:13

bkzland

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TyrantWave · Accepted Answer · 2012-01-12 15:14:05Z

1

If the format is always "YYYY-MM-DD HH:mm:ss", then try this:

date = date[1:11]

In a prompt:

>>> date = '"2012-01-12 15:13:20"'
>>> date[1:11]
'2012-01-12'
>>>

No need for regex

answered Jan 12, 2012 at 15:14

TyrantWave

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kev · Accepted Answer · 2012-01-12 15:14:43Z

1

>>> date = '"2011-10-01 19:25:01"'
>>> date.strip('"').split()[0]
'2011-10-01'

answered Jan 12, 2012 at 15:14

kev

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murgatroid99 · Accepted Answer · 2012-01-12 15:41:55Z

1

One problem with your code is that in your last regular expression, $ matches the end of the string, so that regular expression will never match anything. You could do this much more simply by splitting by spaces and only taking the first result. After removing the quotation marks, the line

date.split()

will return ["2011-10-01", "19:25:01"], so the first element of that list is what you need.

edited Jan 12, 2012 at 15:41

answered Jan 12, 2012 at 15:14

murgatroid99

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