Convert julian date SAC to specific format date

3 次查看（过去 30 天）
Daphne Sagel Aguilar
评论： Walter Roberson 2021-3-23
I need convert: CM.SJC..HHE.D.2015.213.172556.SAC to specific format date, examples: 2015 7 26
Please

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2021-3-12
Ran in:
S = 'CM.SJC..HHE.D.2015.213.172556.SAC';
parts = regexp(S,'\.','split');
year = str2double(parts{6});
doy = str2double(parts{7});
hour = str2double(parts{8}(1:2));
minute = str2double(parts{8}(3:4));
second = str2double(parts{8}(5:6));
output = datetime(year, 1, 1, hour, minute, second, 'Format', 'yyyy M d hh:mm:ss', 'timezone','utc') + days(doy);
output
output = datetime
2015 8 2 05:25:56
days(datetime(2015,7,26)-datetime(2015,1,1))
ans = 206
Could you confirm that you really do have Julian days? Julian Days are number of days since a particular date around 4700 BCE. As you can see, there is a difference of exactly one week between your intended output and a calculation based upon day of the year.
  1 个评论
Daphne Sagel Aguilar
Daphne Sagel Aguilar 2021-3-12
Thank you very much, you have given us a plus in our work. We were working with the length of the SAC file, and with this code we can divide it into parts, excellent.

请先登录，再进行评论。

更多回答（1 个）

Peter Perkins
Peter Perkins 2021-3-23
I'm gonna suggest another solution that might be simpler to follow.
First thing is that this isn't a Julian Date in the strictly correct sense of the word. In many fields though, "Julian day/date" means "day of year". That's what you have.
datetime text conversion will handle literals in a timestamp (the double-quoted format contains single-quote-escaped literals), and will handle day of year ("D", not "d"). So this
>> t1 = 'CM.SJC..HHE.D.2015.213.172556.SAC'
t1 =
'CM.SJC..HHE.D.2015.213.172556.SAC'
>> d1 = datetime(t1,'InputFormat',"'CM.SJC..HHE.D.'uuuu.DDD.HHmmss'.SAC'")
would be the way to go. Unfortunately, there's a fairly recent (and VERY narrowly-scoped) bug in parsing timestamps that causes that to error (thanks, Walter, for reporting it). That will be fixed, but for now, there are two work-arounds. One is to lower-case everything:
>> t2 = lower(t1)
t2 =
'cm.sjc..hhe.d.2015.213.172556.sac'
d2 = datetime(t2,'InputFormat',"'cm.sjc..hhe.d.'uuuu.DDD.HHmmss'.sac'")
d2 =
datetime
01-Aug-2015 17:25:56
The other is to peel off the literals. In versions since R2016b it's easiest to use some string functions rather than regexp:
>> t3 = extractAfter(extractBefore(t1,".SAC"),"CM.SJC..HHE.D.")
t3 =
'2015.213.172556'
d3 = datetime(t3,'InputFormat',"uuuu.DDD.HHmmss")
d3 =
datetime
01-Aug-2015 17:25:56
The above shows scalars, but of course it's completely vectorized.
  1 个评论
Walter Roberson
Walter Roberson 2021-3-23
Ran in:
The regexp version is not so bad
t1 = 'CM.SJC..HHE.D.2015.213.172556.SAC'
t1 = 'CM.SJC..HHE.D.2015.213.172556.SAC'
t3 = regexp(t1, '\d[\d.]+', 'match')
t3 = 1×1 cell array
{'2015.213.172556.'}
d3 = datetime(t3, 'InputFormat', 'uuuu.DDD.HHmmss.')
d3 = datetime
01-Aug-2015 17:25:56

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Dates and Time 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by