Where is time.strptime()?
Fredrik Lundh
fredrik at effbot.org
Sat Nov 4 04:29:16 EST 2000
jschmitt at vmlabs.com wrote:
> I even looked for a 'time.py' in Python20\Lib and didn't find one. Is
> it magic?
no, it's a C module. see:
http://www.python.org/doc/FAQ.html#4.70
4.70. Where is the math.py (socket.py, regex.py, etc.) source file?
> strptime() -- parse string to time tuple according to format
> specification
always check the library reference for the full story:
http://www.python.org/doc/current/lib/module-time.html
"Note: This function relies entirely on the underlying platform's
C library for the date parsing, and some of these libraries are
buggy. There's nothing to be done about this short of a new,
portable implementation of strptime().
Availability: Most modern Unix systems.
in other words, if you cannot see it, it's because your platform
doesn't have it.
:::
here's a pure-Python partial implementation of strptime (reposted,
since I cannot find the original post in dejanews):
# time-example-6.py
# written by fredrik lundh, september 2000
import re
import string
MONTHS = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
"Sep", "Oct", "Nov", "Dec"]
SPEC = {
"%a": "(?P<weekday>[a-z]+)",
"%A": "(?P<weekday>[a-z]+)",
"%b": "(?P<month>[a-z]+)",
"%B": "(?P<month>[a-z]+)",
"%C": "(?P<century>\d\d?)",
"%d": "(?P<day>\d\d?)",
"%D": "(?P<month>\d\d?)/(?P<day>\d\d?)/%y",
"%e": "(?P<day>\d\d?)",
"%h": "(?P<month>[a-z]+)",
"%H": "(?P<hour>\d\d?)",
"%I": "(?P<hour12>\d\d?)",
"%j": "(?P<yearday>\d\d?\d?)",
"%m": "(?P<month>\d\d?)",
"%M": "(?P<minute>\d\d?)",
"%p": "(?P<ampm12>am|pm)",
"%R": "(?P<hour>\d\d?):(?P<minute>\d\d?)",
"%S": "(?P<second>\d\d?)",
"%T": "(?P<hour>\d\d?):(?P<minute>\d\d?):(?P<second>\d\d?)",
"%U": "(?P<week>\d\d)",
"%w": "(?P<weekday>\d)",
"%W": "(?P<weekday>\d\d)",
"%y": "(?P<year>\d\d)",
"%Y": "(?P<year>\d\d\d\d)",
"%%": "%"
}
class TimeParser:
def __init__(self, format):
format = string.join(re.split("(?:\s|%t|%n)+", format))
pattern = []
try:
for spec in re.findall("%\w|%%|.", format):
if spec[0] == "%":
spec = SPEC[spec]
pattern.append(spec)
except KeyError:
raise ValueError, "unknown specificer: %s" % spec
self.pattern = re.compile("(?i)" + string.join(pattern, ""))
def match(self, string):
match = self.pattern.match(string)
if not match:
raise ValueError, "format mismatch"
group = match.group
tm = [0] * 9
y, m, d = group("year", "month", "day")
if y:
y = int(y)
if y < 68:
y = 2000 + y
elif y < 100:
y = 1900 + y
tm[0] = y
if m:
if m in MONTHS:
m = MONTHS.index(m) + 1
tm[1] = int(m)
if d: tm[2] = int(d)
h, m, s = group("hour", "minute", "second")
if h:
tm[3] = int(h)
else:
h = group("hour12")
if h:
h = int(h)
if string.lower(group("ampm")) == "pm":
h = h + 12
tm[3] = int(h)
if m: tm[4] = int(m)
if s: tm[5] = int(s)
# ignore weekday/yearday for now
return tm
def strptime(string, format="%a %b %d %H:%M:%S %Y"):
return TimeParser(format).match(string)
:::
>>> print strptime("2000-12-20 01:02:03", "%Y-%m-%d %H:%M:%S")
[2000, 12, 20, 1, 2, 3, 0, 0, 0]
>>> print strptime(time.ctime(time.time()))
[2000, 9, 12, 10, 31, 43, 0, 0, 0]
:::
also, if you're going to convert lots of dates, creating a TimeParser
instance is more efficient than calling strptime over and over again.
</F>
More information about the Python-list
mailing list