python strptime format with optional bits

Question

Right now I have:

timestamp = datetime.strptime(date_string, \'%Y-%m-%d %H:%M:%S.%f\')

This works great unless I\'m converting a string tha

Answer 1

I prefer using regex matches instead of try and except. This allows for many fallbacks of acceptable formats.

# full timestamp with milliseconds
match = re.match(r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d+Z", date_string)
if match:
    return datetime.strptime(date_string, "%Y-%m-%dT%H:%M:%S.%fZ")

# timestamp missing milliseconds
match = re.match(r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z", date_string)
if match:
    return datetime.strptime(date_string, "%Y-%m-%dT%H:%M:%SZ")

# timestamp missing milliseconds & seconds
match = re.match(r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}Z", date_string)
if match:
    return datetime.strptime(date_string, "%Y-%m-%dT%H:%MZ")

# unknown timestamp format
return false

Don't forget to import "re" as well as "datetime" for this method.

Answer 2

using one regular expression and some list expressions

time_str = "12:34.567"
# time format is [HH:]MM:SS[.FFF]
sum([a*b for a,b in zip(map(lambda x: int(x) if x else 0, re.match(r"(?:(\d{2}):)?(\d{2}):(\d{2})(?:\.(\d{3}))?", time_str).groups()), [3600, 60, 1, 1/1000])])
# result = 754.567

Answer 3

You could use a try/except block:

try:
    timestamp = datetime.strptime(date_string, '%Y-%m-%d %H:%M:%S.%f')
except ValueError:
    timestamp = datetime.strptime(date_string, '%Y-%m-%d %H:%M:%S')

Answer 4

For my similar problem using jq I used the following:

|split("Z")[0]|split(".")[0]|strptime("%Y-%m-%dT%H:%M:%S")|mktime

As the solution to sort my list by time properly.

Answer 5

I'm late to the party but I found if you don't care about the optional bits this will lop off the .%f for you.

datestring.split('.')[0]

Answer 6

What about just appending it if it doesn't exist?

if '.' not in date_string:
    date_string = date_string + '.0'

timestamp = datetime.strptime(date_string, '%Y-%m-%d %H:%M:%S.%f')