1
00:00:00,610 --> 00:00:04,060
So what if you want your date and time in
a certain format,

2
00:00:04,060 --> 00:00:07,770
like you need to print that out all pretty
for a script or on your blog.

3
00:00:07,770 --> 00:00:10,770
Welcome to the warm, wonderful world of
date formatting.

4
00:00:10,770 --> 00:00:12,480
I've put a link in the teacher's notes.

5
00:00:12,480 --> 00:00:16,350
You should probably have this open for the
video and the later code challenges.

6
00:00:16,350 --> 00:00:18,680
Trust me, no one memorizes this.

7
00:00:18,680 --> 00:00:22,269
But complicated or not, it's one of the
most useful areas in the datetime library.

8
00:00:23,670 --> 00:00:25,480
So as you can see, I jumped ahead a little
bit.

9
00:00:25,480 --> 00:00:28,770
I've already got datetime imported and
I've already created our now variable.

10
00:00:28,770 --> 00:00:30,640
Just like we did in the last video.

11
00:00:30,640 --> 00:00:34,540
So lets look at our object once again.

12
00:00:34,540 --> 00:00:38,050
We get this datetime.datetime which tells
us the class and everything and

13
00:00:38,050 --> 00:00:41,010
then we get this spelled out big long
thing of year,

14
00:00:41,010 --> 00:00:44,140
month, day, hour, minute, second,
microsecond.

15
00:00:44,140 --> 00:00:47,730
It's definitely readable, but do we wanna
look at that every single time?

16
00:00:47,730 --> 00:00:50,330
Do we have to look at that every single
time?

17
00:00:50,330 --> 00:00:52,160
Do we have to pull apart the month and

18
00:00:52,160 --> 00:00:56,470
the year attributes in order to get out
our, you know, nice, pretty strings?

19
00:00:56,470 --> 00:00:58,230
No, of course we don't.

20
00:00:58,230 --> 00:01:00,440
Python's not gonna make us do all that
extra work.

21
00:01:00,440 --> 00:01:04,315
So let's look at this function called
strftime.

22
00:01:04,315 --> 00:01:07,130
strftime let's us turn a date, a time, or

23
00:01:07,130 --> 00:01:11,100
a datetime into a string formatted how we
want.

24
00:01:11,100 --> 00:01:17,380
So let's use strftime and let's get out
just the month name and the day number.

25
00:01:17,380 --> 00:01:21,452
So we do now.strftime, and then we have to
pass in a string.

26
00:01:21,452 --> 00:01:25,620
So %B is the month name.

27
00:01:25,620 --> 00:01:28,325
I'm gonna do a space and I'm gonna %d.

28
00:01:28,325 --> 00:01:31,310
And print that and we get October 15th.

29
00:01:31,310 --> 00:01:34,200
So that's handy enough but there's a
problem.

30
00:01:34,200 --> 00:01:39,770
And the problem is that I don't know all
of these strings.

31
00:01:40,945 --> 00:01:44,745
So let's come down here and let's actually
go to

32
00:01:44,745 --> 00:01:50,500
docs.python.org as we do, and let's search
over here for datetime.

33
00:01:50,500 --> 00:01:54,790
And here's our datetime module, and if we
look down here,

34
00:01:54,790 --> 00:01:59,050
we have this strftime and strptime
behavior.

35
00:01:59,050 --> 00:02:01,960
And there's this awesome, awesome table
here showing me everything.

36
00:02:01,960 --> 00:02:06,510
So you can see I did %B, and I got the
full name in my current local.

37
00:02:06,510 --> 00:02:09,420
So if I was in Germany, I'd get a
different name.

38
00:02:09,420 --> 00:02:12,280
If I was in Spain, I'd get a different
name, so on and so forth.

39
00:02:12,280 --> 00:02:15,000
Since I'm in the US, I get January,
February, whatever.

40
00:02:15,000 --> 00:02:20,340
Okay, so what I want is I want what we
consider like a US

41
00:02:20,340 --> 00:02:26,040
standard time stamp, which is one where
it's month, day, year.

42
00:02:26,040 --> 00:02:26,560
Okay.

43
00:02:26,560 --> 00:02:30,000
So now.strftime, and I have to pass in a
string.

44
00:02:30,000 --> 00:02:32,350
So let's find month.

45
00:02:33,510 --> 00:02:34,180
Here it is.

46
00:02:34,180 --> 00:02:35,930
Month as zero-padded decimal number.

47
00:02:35,930 --> 00:02:39,930
So that's %m, okay, %m.

48
00:02:39,930 --> 00:02:42,700
And I'm gonna do a slash and I'm gonna do
%d is the day.

49
00:02:42,700 --> 00:02:45,720
Cuz I did that before and then now I want
the year.

50
00:02:45,720 --> 00:02:48,380
And I want, well, so let's see.

51
00:02:48,380 --> 00:02:53,260
We have here year without century so we
get like 01 or

52
00:02:53,260 --> 00:02:55,120
14 which is what we're gonna get.

53
00:02:55,120 --> 00:03:00,259
Or year with century and we'd get a longer
number like 2013, 2014.

54
00:03:00,259 --> 00:03:01,618
Let's do the shorter number.

55
00:03:01,618 --> 00:03:04,129
And we're going to do %y.

56
00:03:04,129 --> 00:03:09,326
[NOISE] We press Return and we get
10/15/14.

57
00:03:09,326 --> 00:03:11,690
All right, so that's it.

58
00:03:11,690 --> 00:03:15,810
The hardest part of this is really
referring back to those datetime docs.

59
00:03:15,810 --> 00:03:21,880
Finding exactly which one you want in this
table is not always the easiest thing.

60
00:03:21,880 --> 00:03:26,380
Sometimes it takes a little bit of reading
to figure out which one that you're doing.

61
00:03:26,380 --> 00:03:29,890
So bookmark this, keep it handy, you're
gonna be using this a lot.

62
00:03:29,890 --> 00:03:32,900
It's definitely a very, very useful thing
to have around.

63
00:03:33,980 --> 00:03:38,150
I mentioned that we're also gonna talk
about an strptime function.

64
00:03:38,150 --> 00:03:43,410
Now sadly, strftime and strptime are
nearly identical.

65
00:03:43,410 --> 00:03:45,460
There's one letter difference, F or P.

66
00:03:45,460 --> 00:03:47,750
So, you're probably gonna end up confusing
them.

67
00:03:47,750 --> 00:03:49,040
I know I do.

68
00:03:49,040 --> 00:03:54,860
But I've started thinking of them in this
way, strftime is string from time,

69
00:03:54,860 --> 00:03:56,700
or string formatted time.

70
00:03:56,700 --> 00:04:00,550
And strptime is string parsed into time.

71
00:04:00,550 --> 00:04:05,670
So, hopefully that pneumonic, depending on
how good it is, will help you.

72
00:04:05,670 --> 00:04:07,580
So what does strptime do?

73
00:04:07,580 --> 00:04:09,240
I keep saying it, we keep talking about
it, but

74
00:04:09,240 --> 00:04:11,040
we haven't talked about what it does yet.

75
00:04:11,040 --> 00:04:15,910
So it let's us make a datetime from a
string with a certain format.

76
00:04:15,910 --> 00:04:17,560
Okay, so, let's do this.

77
00:04:17,560 --> 00:04:23,380
Let's say birthday, datetime.strptime and

78
00:04:23,380 --> 00:04:26,960
then we pass in a string that represents
the date.

79
00:04:26,960 --> 00:04:30,990
So let's do 2015-04-21.

80
00:04:30,990 --> 00:04:34,660
Which would be the 21st of April next
year.

81
00:04:34,660 --> 00:04:37,382
This isn't my birthday, just a random
date.

82
00:04:37,382 --> 00:04:42,210
All right, so, but now what I have to do
is I have to explain

83
00:04:42,210 --> 00:04:45,890
to datetime how this string is formatted.

84
00:04:45,890 --> 00:04:50,594
And I do that with the same string types
that we used in strftime.

85
00:04:50,594 --> 00:04:54,310
So, I remember that %Y is the year.

86
00:04:54,310 --> 00:04:58,420
Let's look that up just to make sure, and
there it is.

87
00:04:58,420 --> 00:04:59,540
That's the long year.

88
00:04:59,540 --> 00:05:00,820
Okay.

89
00:05:00,820 --> 00:05:04,960
And then we do hyphen and we do %m,
hyphen, %d, all right.

90
00:05:04,960 --> 00:05:08,019
So the only thing different here is kind
of the order they're in, and

91
00:05:08,019 --> 00:05:09,781
we used a cap Y instead of a lower case Y.

92
00:05:09,781 --> 00:05:12,282
Oh, sorry, it is datetime.datetime.

93
00:05:12,282 --> 00:05:17,788
[BLANK_AUDIO]

94
00:05:17,788 --> 00:05:19,330
And I missed my dot.

95
00:05:21,510 --> 00:05:23,010
There we go, okay.

96
00:05:23,010 --> 00:05:26,880
So now, we should be able to look at
birthday and

97
00:05:26,880 --> 00:05:28,730
there's our datetime that was created.

98
00:05:28,730 --> 00:05:33,229
Now, you notice there's no there's no
hours on this because we didn't have any

99
00:05:33,229 --> 00:05:35,050
hours specified in our strptime.

100
00:05:35,050 --> 00:05:36,390
But that only had the date.

101
00:05:36,390 --> 00:05:39,190
What if we wanted to include a time as
well?

102
00:05:39,190 --> 00:05:41,710
So let's do birthday_party.

103
00:05:41,710 --> 00:05:44,080
Because this is when the party is.

104
00:05:44,080 --> 00:05:47,820
So datetime.datetime.strptime.

105
00:05:47,820 --> 00:05:52,122
And we'll do 2015 again, and 04 again, and
21.

106
00:05:52,122 --> 00:05:57,520
And then we'll do a space, and then we'll
do 09, colon, 00.

107
00:05:57,520 --> 00:06:00,130
Okay, so this is a lot more to explain.

108
00:06:00,130 --> 00:06:01,064
We're having the birthday party, you know
what?

109
00:06:01,064 --> 00:06:03,470
Let's have the birthday party at noon
instead.

110
00:06:05,000 --> 00:06:06,763
All right, how do we describe this one?

111
00:06:06,763 --> 00:06:08,480
Well, the beginning is still the same.

112
00:06:09,830 --> 00:06:13,090
So it's that.
And then we put in a literal space.

113
00:06:13,090 --> 00:06:14,860
And then I need hours.

114
00:06:17,450 --> 00:06:18,120
And, let's see.

115
00:06:18,120 --> 00:06:23,769
Hours are capital H, all right.

116
00:06:23,769 --> 00:06:28,640
Capital H, colon, and I know that capital
M is minutes.

117
00:06:28,640 --> 00:06:31,950
You start to memorize some of these as you
go through.

118
00:06:31,950 --> 00:06:34,464
And now let's look at birthday_party.

119
00:06:34,464 --> 00:06:36,950
And there's our time and it's set at noon.

120
00:06:36,950 --> 00:06:39,900
All right, so we have everything we put in
there.

121
00:06:39,900 --> 00:06:43,500
Now, I want you to notice, I did the
capital H so it's a 24-hour clock.

122
00:06:43,500 --> 00:06:47,310
So like 1 PM would be 13, 6 PM would be
18.

123
00:06:47,310 --> 00:06:50,140
I do that so I don't have to specify AM or
PM.

124
00:06:50,140 --> 00:06:53,920
There is a flag you can put in for AM and
PM if you wanna use those,

125
00:06:53,920 --> 00:06:55,220
if that's more comfortable to you.

126
00:06:55,220 --> 00:06:58,442
So you have full control of this.

127
00:06:58,442 --> 00:07:01,990
Turning datetime objects into strings, or
strings into datetimes,

128
00:07:01,990 --> 00:07:05,590
is mostly a matter of remembering or
looking up the format strings.

129
00:07:05,590 --> 00:07:08,220
I'm sure you can see it's also pretty
handy.

130
00:07:08,220 --> 00:07:10,280
Actually, I have a challenge for you now.

131
00:07:10,280 --> 00:07:13,438
Using the Python docs, and strftime and

132
00:07:13,438 --> 00:07:16,490
strptime, make a script that accepts a
month and

133
00:07:16,490 --> 00:07:21,910
day date in whatever format you want that
returns a link to Wikipedia for that date.

134
00:07:21,910 --> 00:07:24,700
Be sure you tell the user how to format
their data for you.

135
00:07:24,700 --> 00:07:26,690
Come back in the next video and we'll
build it together.