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I am able to parse strings containing date/time with time.strptime

>>> import time >>> time.strptime('30/03/09 16:31:32', '%d/%m/%y %H:%M:%S') (2009, 3, 30, 16, 31, 32, 0, 89, -1)

How can I parse a time string that contains milliseconds?

>>> time.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S') Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.5/_strptime.py", line 333, in strptime data_string[found.end():]) ValueError: unconverted data remains: .123
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8 Answers 8

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436

Python 2.6 added a new strftime/strptime macro %f. The docs are a bit misleading as they only mention microseconds, but %f actually parses any decimal fraction of seconds with up to 6 digits, meaning it also works for milliseconds or even centiseconds or deciseconds.

time.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f')

However, time.struct_time doesn't actually store milliseconds/microseconds. You're better off using datetime, like this:

>>> from datetime import datetime >>> a = datetime.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f') >>> a.microsecond 123000

As you can see, .123 is correctly interpreted as 123 000 microseconds.

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12 Comments

Thanks docs.python.org/library/datetime.html : New in version 2.6: time and datetime objects support a %f format code which expands to the number of microseconds in the object, zero-padded on the left to six places.
Woa I can tell the the Python docs needs updating. Docs for the time module doesn't say anything about %f.
The Python docs, as of version 2.7.3, are a bit misleading. For strptime, %f can actually represent any number of decimal places, not just 6, as one might expect for microseconds. So the code above would parse 32.123 seconds and store it as 123,000µs, which is what we want.
The number in %f is padded with zeros on the right (not left!) to 6 decimal places. 1 gets parsed to 100000, 12 gets parsed to 120000, and 1234567 produces ValueError: unconverted data remains: 7
Is it just me or was the question about milliseconds, not microseconds?
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13

I know this is an older question but I'm still using Python 2.4.3 and I needed to find a better way of converting the string of data to a datetime.

The solution if datetime doesn't support %f and without needing a try/except is:

(dt, mSecs) = row[5].strip().split(".") dt = datetime.datetime(*time.strptime(dt, "%Y-%m-%d %H:%M:%S")[0:6]) mSeconds = datetime.timedelta(microseconds = int(mSecs)) fullDateTime = dt + mSeconds

This works for the input string "2010-10-06 09:42:52.266000"

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2 Comments

dt.replace(microsecond=int(mSecs))
This applies to Python 2.5 and earlier. Python 2.6 supports strptime '%f'
4

To give the code that nstehr's answer refers to (from its source):

def timeparse(t, format): """Parse a time string that might contain fractions of a second. Fractional seconds are supported using a fragile, miserable hack. Given a time string like '02:03:04.234234' and a format string of '%H:%M:%S', time.strptime() will raise a ValueError with this message: 'unconverted data remains: .234234'. If %S is in the format string and the ValueError matches as above, a datetime object will be created from the part that matches and the microseconds in the time string. """ try: return datetime.datetime(*time.strptime(t, format)[0:6]).time() except ValueError, msg: if "%S" in format: msg = str(msg) mat = re.match(r"unconverted data remains:" " \.([0-9]{1,6})$", msg) if mat is not None: # fractional seconds are present - this is the style # used by datetime's isoformat() method frac = "." + mat.group(1) t = t[:-len(frac)] t = datetime.datetime(*time.strptime(t, format)[0:6]) microsecond = int(float(frac)*1e6) return t.replace(microsecond=microsecond) else: mat = re.match(r"unconverted data remains:" " \,([0-9]{3,3})$", msg) if mat is not None: # fractional seconds are present - this is the style # used by the logging module frac = "." + mat.group(1) t = t[:-len(frac)] t = datetime.datetime(*time.strptime(t, format)[0:6]) microsecond = int(float(frac)*1e6) return t.replace(microsecond=microsecond) raise
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4

DNS answer above is actually incorrect. The SO is asking about milliseconds but the answer is for microseconds. Unfortunately, Python`s doesn't have a directive for milliseconds, just microseconds (see doc), but you can workaround it by appending three zeros at the end of the string and parsing the string as microseconds, something like:

datetime.strptime(time_str + '000', '%d/%m/%y %H:%M:%S.%f')

where time_str is formatted like 30/03/09 16:31:32.123.

Hope this helps.

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1 Comment

I thought the same thing initially, but see the comments on the answer and the docs. It's left-zero-padded microseconds, so .123 is correctly interpreted as 123,000 microseconds
1

My first thought was to try passing it '30/03/09 16:31:32.123' (with a period instead of a colon between the seconds and the milliseconds.) But that didn't work. A quick glance at the docs indicates that fractional seconds are ignored in any case...

Ah, version differences. This was reported as a bug and now in 2.6+ you can use "%S.%f" to parse it.

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That doesn't work; time.strptime just doesn't do milliseconds.
1

from python mailing lists: parsing millisecond thread. There is a function posted there that seems to get the job done, although as mentioned in the author's comments it is kind of a hack. It uses regular expressions to handle the exception that gets raised, and then does some calculations.

You could also try do the regular expressions and calculations up front, before passing it to strptime.

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yes, i know that thread. But i am looking for a simpler way. is there any module in the standart python lib that makes the time parsing with milliseconds?
1

For python 2 i did this

print ( time.strftime("%H:%M:%S", time.localtime(time.time())) + "." + str(time.time()).split(".",1)[1])

it prints time "%H:%M:%S" , splits the time.time() to two substrings (before and after the .) xxxxxxx.xx and since .xx are my milliseconds i add the second substring to my "%H:%M:%S"

hope that makes sense :) Example output:

13:31:21.72 Blink 01

13:31:21.81 END OF BLINK 01

13:31:26.3 Blink 01

13:31:26.39 END OF BLINK 01

13:31:34.65 Starting Lane 01

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0

It detects the format with fromisoformat, but the challenge lies in writing it.

Creating a custom formatter is the most convenient method that I have discovered.

from datetime import datetime import pytz d = datetime.fromisoformat("2022-08-05 08:47:50.17+00").astimezone(pytz.utc) print(f"{d.year:04d}-{d.month:02d}-{d.day:02d}T{d.hour:02d}:{d.minute:02d}:{d.second:02d}.{int(d.microsecond/1000):02d}Z")

So, the formatted value is: 2022-08-05T08:47:50.170Z

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