1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
=============
relativedelta
=============
.. automodule:: dateutil.relativedelta
:members:
:undoc-members:
.. testsetup:: relativedelta
Examples
--------
>>> from datetime import *; from dateutil.relativedelta import *
>>> import calendar
>>> NOW = datetime(2003, 9, 17, 20, 54, 47, 282310)
>>> TODAY = date(2003, 9, 17)
Let's begin our trip::
>>> from datetime import *; from dateutil.relativedelta import *
>>> import calendar
Store some values::
>>> NOW = datetime.now()
>>> TODAY = date.today()
>>> NOW
datetime.datetime(2003, 9, 17, 20, 54, 47, 282310)
>>> TODAY
datetime.date(2003, 9, 17)
Next month
.. doctest:: relativedelta
>>> NOW+relativedelta(months=+1)
datetime.datetime(2003, 10, 17, 20, 54, 47, 282310)
Next month, plus one week.
.. doctest:: relativedelta
>>> NOW+relativedelta(months=+1, weeks=+1)
datetime.datetime(2003, 10, 24, 20, 54, 47, 282310)
Next month, plus one week, at 10am.
.. doctest:: relativedelta
>>> TODAY+relativedelta(months=+1, weeks=+1, hour=10)
datetime.datetime(2003, 10, 24, 10, 0)
Here is another example using an absolute relativedelta. Notice the use of
year and month (both singular) which causes the values to be *replaced* in the
original datetime rather than performing an arithmetic operation on them.
.. doctest:: relativedelta
>>> NOW+relativedelta(year=1, month=1)
datetime.datetime(1, 1, 17, 20, 54, 47, 282310)
Let's try the other way around. Notice that the
hour setting we get in the relativedelta is relative,
since it's a difference, and the weeks parameter
has gone.
.. doctest:: relativedelta
>>> relativedelta(datetime(2003, 10, 24, 10, 0), TODAY)
relativedelta(months=+1, days=+7, hours=+10)
One month before one year.
.. doctest:: relativedelta
>>> NOW+relativedelta(years=+1, months=-1)
datetime.datetime(2004, 8, 17, 20, 54, 47, 282310)
How does it handle months with different numbers of days?
Notice that adding one month will never cross the month
boundary.
.. doctest:: relativedelta
>>> date(2003,1,27)+relativedelta(months=+1)
datetime.date(2003, 2, 27)
>>> date(2003,1,31)+relativedelta(months=+1)
datetime.date(2003, 2, 28)
>>> date(2003,1,31)+relativedelta(months=+2)
datetime.date(2003, 3, 31)
The logic for years is the same, even on leap years.
If the result falls on a day after the last one of the month, the last day of the month is used instead.
.. doctest::
>>> date(2003,1,30)+relativedelta(months=+1)
datetime.date(2003, 2, 28)
>>> date(2003,5,31)+relativedelta(months=-1)
datetime.date(2003, 4, 30)
.. doctest:: relativedelta
>>> date(2000,2,28)+relativedelta(years=+1)
datetime.date(2001, 2, 28)
>>> date(2000,2,29)+relativedelta(years=+1)
datetime.date(2001, 2, 28)
>>> date(1999,2,28)+relativedelta(years=+1)
datetime.date(2000, 2, 28)
>>> date(1999,3,1)+relativedelta(years=+1)
datetime.date(2000, 3, 1)
>>> date(2001,2,28)+relativedelta(years=-1)
datetime.date(2000, 2, 28)
>>> date(2001,3,1)+relativedelta(years=-1)
datetime.date(2000, 3, 1)
Next friday
.. doctest:: relativedelta
>>> TODAY+relativedelta(weekday=FR)
datetime.date(2003, 9, 19)
>>> TODAY+relativedelta(weekday=calendar.FRIDAY)
datetime.date(2003, 9, 19)
Last friday in this month.
.. doctest:: relativedelta
>>> TODAY+relativedelta(day=31, weekday=FR(-1))
datetime.date(2003, 9, 26)
Next wednesday (it's today!).
.. doctest:: relativedelta
>>> TODAY+relativedelta(weekday=WE(+1))
datetime.date(2003, 9, 17)
Next wednesday, but not today.
.. doctest:: relativedelta
>>> TODAY+relativedelta(days=+1, weekday=WE(+1))
datetime.date(2003, 9, 24)
Following
`ISO year week number notation <https://www.cl.cam.ac.uk/~mgk25/iso-time.html>`_
find the first day of the 15th week of 1997.
.. doctest:: relativedelta
>>> datetime(1997,1,1)+relativedelta(day=4, weekday=MO(-1), weeks=+14)
datetime.datetime(1997, 4, 7, 0, 0)
How long ago has the millennium changed?
.. doctest:: relativedelta
:options: +NORMALIZE_WHITESPACE
>>> relativedelta(NOW, date(2001,1,1))
relativedelta(years=+2, months=+8, days=+16,
hours=+20, minutes=+54, seconds=+47, microseconds=+282310)
How old is John?
.. doctest:: relativedelta
:options: +NORMALIZE_WHITESPACE
>>> johnbirthday = datetime(1978, 4, 5, 12, 0)
>>> relativedelta(NOW, johnbirthday)
relativedelta(years=+25, months=+5, days=+12,
hours=+8, minutes=+54, seconds=+47, microseconds=+282310)
It works with dates too.
.. doctest:: relativedelta
>>> relativedelta(TODAY, johnbirthday)
relativedelta(years=+25, months=+5, days=+11, hours=+12)
Obtain today's date using the yearday:
.. doctest:: relativedelta
>>> date(2003, 1, 1)+relativedelta(yearday=260)
datetime.date(2003, 9, 17)
We can use today's date, since yearday should be absolute
in the given year:
.. doctest:: relativedelta
>>> TODAY+relativedelta(yearday=260)
datetime.date(2003, 9, 17)
Last year it should be in the same day:
.. doctest:: relativedelta
>>> date(2002, 1, 1)+relativedelta(yearday=260)
datetime.date(2002, 9, 17)
But not in a leap year:
.. doctest:: relativedelta
>>> date(2000, 1, 1)+relativedelta(yearday=260)
datetime.date(2000, 9, 16)
We can use the non-leap year day to ignore this:
.. doctest:: relativedelta
>>> date(2000, 1, 1)+relativedelta(nlyearday=260)
datetime.date(2000, 9, 17)
|
