python - 如何从 python time.time() 计算当前月份

Question

我正在尝试获取当前月数 3(今天是 04.03.2016)。所以我在运行:

from time import time
Ys=12*30*24*3600
Ms=Ys/12
m=(trunc(time())%Ys)/Ms
print m

结果是 10。

有趣的是，当我运行时:

Ds=Ms/30
d=(trunc(time())%Ms)/Ds

那么结果是正确的:4.

为什么 m 不是 3 而是 10？

Answer 1

下面介绍了如何在不使用任何库函数的情况下将 Unix 纪元时间转换为 (UTC) Gregorian 日期。下面的代码仅导入 time 以验证计算出的日期与 time.gmtime 返回的日期相同。

请注意，在 2038 年 1 月 19 日星期二 03:14:08 UTC，32 位版本的 Unix 时间戳将停止工作，因为它会溢出签名 32-位数。因此，不要尝试在 32 位系统上调用 time.gmtime 以获得此类时间戳。当然，下面使用的算法不受这些限制。

#!/usr/bin/env python

''' Convert Unix Epoch seconds to (proleptic) Gregorian date

    Algorithm by E. G. Richards, https://en.wikipedia.org/wiki/Julian_day

    See http://stackoverflow.com/q/35796786/4014959

    Python implementation by PM 2Ring 2016.03.07
'''

from time import gmtime

def epoch_seconds_to_gregorian_date(eseconds):
    # Algorithm parameters for Gregorian calendar
    y = 4716; j = 1401; m = 2; n = 12; r = 4; p = 1461 
    v = 3; u = 5; s = 153; w = 2; B = 274277; C = -38

    #Julian day, rounded
    J = int(0.5 + eseconds / 86400.0 + 2440587.5)

    f = J + j + (((4 * J + B) // 146097) * 3) // 4 + C
    e = r * f + v
    g = (e % p) // r
    h = u * g + w
    D = (h % s) // u + 1
    M = (h // s + m) % n + 1
    Y = (e // p) - y + (n + m - M) // n

    return Y, M, D

# Tests    
def test(s):
    t = gmtime(s)
    gmdate = t.tm_year, t.tm_mon, t.tm_mday
    e2gdate = epoch_seconds_to_gregorian_date(s)
    assert gmdate == e2gdate, (t, gmdate, e2gdate)
    return '%d.%d.%d' % e2gdate    

print 'hours'
for i in xrange(25):
    s = 3600 * i
    print i, test(s) 

print '\ndays'
for i in xrange(32):
    s = 86400 * i
    print i, test(s)

print '\n2 days by seconds...'
for s in xrange(86400 * 2):
    test(s)

n = 50
print '\n%d years by days...' % n
for i in xrange(365 * n):
    s = 86400 * i    
    test(s)

print 'Ok'    

输出

hours
0 1970.1.1
1 1970.1.1
2 1970.1.1
3 1970.1.1
4 1970.1.1
5 1970.1.1
6 1970.1.1
7 1970.1.1
8 1970.1.1
9 1970.1.1
10 1970.1.1
11 1970.1.1
12 1970.1.1
13 1970.1.1
14 1970.1.1
15 1970.1.1
16 1970.1.1
17 1970.1.1
18 1970.1.1
19 1970.1.1
20 1970.1.1
21 1970.1.1
22 1970.1.1
23 1970.1.1
24 1970.1.2

days
0 1970.1.1
1 1970.1.2
2 1970.1.3
3 1970.1.4
4 1970.1.5
5 1970.1.6
6 1970.1.7
7 1970.1.8
8 1970.1.9
9 1970.1.10
10 1970.1.11
11 1970.1.12
12 1970.1.13
13 1970.1.14
14 1970.1.15
15 1970.1.16
16 1970.1.17
17 1970.1.18
18 1970.1.19
19 1970.1.20
20 1970.1.21
21 1970.1.22
22 1970.1.23
23 1970.1.24
24 1970.1.25
25 1970.1.26
26 1970.1.27
27 1970.1.28
28 1970.1.29
29 1970.1.30
30 1970.1.31
31 1970.2.1

2 days by seconds...

50 years by days...
Ok

---

这是一个改进的版本，它还返回小时、分钟和秒。此代码处理小数秒，但是，time.struct_time 的字段都是整数，因此我的test 函数不能与小数秒一起使用。

#!/usr/bin/env python

''' Convert Unix Epoch seconds to (proleptic) Gregorian date

    Algorithm by E. G. Richards, https://en.wikipedia.org/wiki/Julian_day

    See http://stackoverflow.com/q/35796786/4014959

    Python implementation by PM 2Ring 2016.03.07
'''

from time import time, gmtime
from random import randint
import sys    

def epoch_seconds_to_gregorian_date(eseconds):
    # Algorithm parameters for Gregorian calendar
    y = 4716; j = 1401; m = 2; n = 12; r = 4; p = 1461 
    v = 3; u = 5; s = 153; w = 2; B = 274277; C = -38

    #Julian day, rounded
    J = int(0.5 + eseconds / 86400.0 + 2440587.5)

    #Date calculation
    f = J + j + (((4 * J + B) // 146097) * 3) // 4 + C
    e = r * f + v
    g = (e % p) // r
    h = u * g + w
    D = (h % s) // u + 1
    M = (h // s + m) % n + 1
    Y = (e // p) - y + (n + m - M) // n

    #Time calculation
    seconds = eseconds % 86400
    t = int(seconds)
    hr, t = divmod(t, 3600)
    mn = t // 60
    seconds -= 3600 * hr + 60 * mn

    return Y, M, D, hr, mn, seconds

# Tests
def test(s):
    t = gmtime(s)
    gmdate = t.tm_year, t.tm_mon, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec
    e2gdate = epoch_seconds_to_gregorian_date(s)
    assert gmdate == e2gdate, (s, gmdate, e2gdate)
    return '%d.%02d.%02d %02d:%02d:%06.3f' % e2gdate

print 'now'
s = time()
print s, epoch_seconds_to_gregorian_date(s), gmtime(s)

print '\nhours'
for i in xrange(25):
    s = 3600 * i
    print i, test(s) 

print '\ndays'
for i in xrange(32):
    s = 86400 * i
    print i, test(s)

print '\n2 days by seconds...'
for i in xrange(86400 * 2):
    test(i)
    if i % 10000 == 0:
        sys.stderr.write('.')
sys.stderr.write('\n')

n = 50
print '\n%d years by days...' % n
for i in xrange(365 * n):
    s = 86400 * i    
    test(s)    

n = 500000
print '\nRandom seconds'
for i in xrange(n):
    s = randint(0, 2147483647)
    test(s)
    if i % 10000 == 0:
        sys.stderr.write('.')
sys.stderr.write('\n')

print 'Ok'

输出

now
1457355412.48 (2016, 3, 7, 12, 56, 52.476011991500854) time.struct_time(tm_year=2016, tm_mon=3, tm_mday=7, tm_hour=12, tm_min=56, tm_sec=52, tm_wday=0, tm_yday=67, tm_isdst=0)

hours
0 1970.01.01 00:00:00.000
1 1970.01.01 01:00:00.000
2 1970.01.01 02:00:00.000
3 1970.01.01 03:00:00.000
4 1970.01.01 04:00:00.000
5 1970.01.01 05:00:00.000
6 1970.01.01 06:00:00.000
7 1970.01.01 07:00:00.000
8 1970.01.01 08:00:00.000
9 1970.01.01 09:00:00.000
10 1970.01.01 10:00:00.000
11 1970.01.01 11:00:00.000
12 1970.01.01 12:00:00.000
13 1970.01.01 13:00:00.000
14 1970.01.01 14:00:00.000
15 1970.01.01 15:00:00.000
16 1970.01.01 16:00:00.000
17 1970.01.01 17:00:00.000
18 1970.01.01 18:00:00.000
19 1970.01.01 19:00:00.000
20 1970.01.01 20:00:00.000
21 1970.01.01 21:00:00.000
22 1970.01.01 22:00:00.000
23 1970.01.01 23:00:00.000
24 1970.01.02 00:00:00.000

days
0 1970.01.01 00:00:00.000
1 1970.01.02 00:00:00.000
2 1970.01.03 00:00:00.000
3 1970.01.04 00:00:00.000
4 1970.01.05 00:00:00.000
5 1970.01.06 00:00:00.000
6 1970.01.07 00:00:00.000
7 1970.01.08 00:00:00.000
8 1970.01.09 00:00:00.000
9 1970.01.10 00:00:00.000
10 1970.01.11 00:00:00.000
11 1970.01.12 00:00:00.000
12 1970.01.13 00:00:00.000
13 1970.01.14 00:00:00.000
14 1970.01.15 00:00:00.000
15 1970.01.16 00:00:00.000
16 1970.01.17 00:00:00.000
17 1970.01.18 00:00:00.000
18 1970.01.19 00:00:00.000
19 1970.01.20 00:00:00.000
20 1970.01.21 00:00:00.000
21 1970.01.22 00:00:00.000
22 1970.01.23 00:00:00.000
23 1970.01.24 00:00:00.000
24 1970.01.25 00:00:00.000
25 1970.01.26 00:00:00.000
26 1970.01.27 00:00:00.000
27 1970.01.28 00:00:00.000
28 1970.01.29 00:00:00.000
29 1970.01.30 00:00:00.000
30 1970.01.31 00:00:00.000
31 1970.02.01 00:00:00.000

2 days by seconds...
..................

50 years by days...

Random seconds
..................................................
Ok