strptime 不完全实现
复制代码 代码示例:
import re
import string
MONTHS = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
"Sep", "Oct", "Nov", "Dec"]
SPEC = {
# map formatting code to a regular expression fragment
"%a": "(?P<weekday>[a-z]+)",
"%A": "(?P<weekday>[a-z]+)",
"%b": "(?P<month>[a-z]+)",
"%B": "(?P<month>[a-z]+)",
"%C": "(?P<century>dd?)",
"%d": "(?P<day>dd?)",
"%D": "(?P<month>dd?)/(?P<day>dd?)/(?P<year>dd)",
"%e": "(?P<day>dd?)",
"%h": "(?P<month>[a-z]+)",
"%H": "(?P<hour>dd?)",
"%I": "(?P<hour12>dd?)",
"%j": "(?P<yearday>dd?d?)",
"%m": "(?P<month>dd?)",
"%M": "(?P<minute>dd?)",
"%p": "(?P<ampm12>am|pm)",
"%R": "(?P<hour>dd?):(?P<minute>dd?)",
"%S": "(?P<second>dd?)",
"%T": "(?P<hour>dd?):(?P<minute>dd?):(?P<second>dd?)",
"%U": "(?P<week>dd)",
"%w": "(?P<weekday>d)",
"%W": "(?P<weekday>dd)",
"%y": "(?P<year>dd)",
"%Y": "(?P<year>dddd)",
"%%": "%"
}
class TimeParser:
def _ _init_ _(self, format):
# convert strptime format string to regular expression
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, daytime):
# match time string
match = self.pattern.match(daytime)
if not match:
raise ValueError, "format mismatch"
get = match.groupdict().get
tm = [0] * 9
# extract date elements
y = get("year")
if y:
y = int(y)
if y < 68:
y = 2000 + y
elif y < 100:
y = 1900 + y
tm[0] = y
m = get("month")
if m:
if m in MONTHS:
m = MONTHS.index(m) + 1
tm[1] = int(m)
d = get("day")
if d: tm[2] = int(d)
# extract time elements
h = get("hour")
if h:
tm[3] = int(h)
else:
h = get("hour12")
if h:
h = int(h)
if string.lower(get("ampm12", "")) == "pm":
h = h + 12
tm[3] = h
m = get("minute")
if m: tm[4] = int(m)
s = get("second")
if s: tm[5] = int(s)
# ignore weekday/yearday for now
return tuple(tm)
def strptime(string, format="%a %b %d %H:%M:%S %Y"):
return TimeParser(format).match(string)
if _ _name_ _ == "_ _main_ _":
# try it out
import time
print strptime("2000-12-20 01:02:03", "%Y-%m-%d %H:%M:%S")
print strptime(time.ctime(time.time()))
(2000, 12, 20, 1, 2, 3, 0, 0, 0)
(2000, 11, 15, 12, 30, 45, 0, 0, 0)
使用 time 模块将本地时间元组转换为时间值(整数)
复制代码 代码示例:
import time
t0 = time.time()
tm = time.localtime(t0)
print tm
print t0
print time.mktime(tm)
(1999, 9, 9, 0, 11, 8, 3, 252, 1)
936828668.16
936828668.0
将 UTC 时间元组转换为时间值(整数)
复制代码 代码示例:
import time
def _d(y, m, d, days=(0,31,59,90,120,151,181,212,243,273,304,334,365)):
# map a date to the number of days from a reference point
return (((y - 1901)*1461)/4 + days[m-1] + d +
((m > 2 and not y % 4 and (y % 100 or not y % 400)) and 1))
def timegm(tm, epoch=_d(1970,1,1)):
year, month, day, h, m, s = tm[:6]
assert year >= 1970
assert 1 <= month <= 12
return (_d(year, month, day) - epoch)*86400 + h*3600 + m*60 + s
t0 = time.time()
tm = time.gmtime(t0)
print tm
print t0
print timegm(tm)
(1999, 9, 8, 22, 12, 12, 2, 251, 0)
936828732.48
936828732
使用 time 模块评价算法
复制代码 代码示例:
import time
def procedure():
time.sleep(2.5)
# measure process time
t0 = time.clock()
procedure()
print time.clock() - t0, "seconds process time"
# measure wall time
t0 = time.time()
procedure()
print time.time() - t0, "seconds wall time"
0.0 seconds process time
2.50903499126 seconds wall time
使用 types 模块
复制代码 代码示例:
import types
def check(object):
print object,
if type(object) is types.IntType:
print "INTEGER",
if type(object) is types.FloatType:
print "FLOAT",
if type(object) is types.StringType:
print "STRING",
if type(object) is types.ClassType:
print "CLASS",
if type(object) is types.InstanceType:
print "INSTANCE",
print
check(0)
check(0.0)
check("0")
class A:
pass
class B:
pass
check(A)
check(B)
a = A()
b = B()
check(a)
check(b)
0 INTEGER
0.0 FLOAT
0 STRING
A CLASS
B CLASS
<A instance at 796960> INSTANCE
<B instance at 796990> INSTANCE
使用 gc 模块收集循环引用垃圾
复制代码 代码示例:
import gc
# create a simple object that links to itself
class Node:
def _ _init_ _(self, name):
self.name = name
self.parent = None
self.children = []
def addchild(self, node):
node.parent = self
self.children.append(node)
def _ _repr_ _(self):
return "<Node %s at %x>" % (repr(self.name), id(self))
# set up a self-referencing structure
root = Node("monty")
root.addchild(Node("eric"))
root.addchild(Node("john"))
root.addchild(Node("michael"))
# remove our only reference
del root
print gc.collect(), "unreachable objects"
print gc.collect(), "unreachable objects"
12 unreachable objects
0 unreachable objects
