I want to be able to get "mmm-yy" in BigQuery. What is the best way to do this. For example "Dec-20"
Use %b-%y instead:
select FORMAT_DATETIME("%b-%y", DATETIME(Current_date()))
Format elements:
%A The full weekday name.
%a The abbreviated weekday name.
%B The full month name.
%b or %h The abbreviated month name.
%C The century (a year divided by 100 and truncated to an integer) as a decimal number (00-99).
%D The date in the format %m/%d/%y.
%d The day of the month as a decimal number (01-31).
%e The day of month as a decimal number (1-31); single digits are preceded by a space.
%F The date in the format %Y-%m-%d.
%G The ISO 8601 year with century as a decimal number. Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %G and %Y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%g The ISO 8601 year without century as a decimal number (00-99). Each ISO year begins on the Monday before the first Thursday of the Gregorian calendar year. Note that %g and %y may produce different results near Gregorian year boundaries, where the Gregorian year and ISO year can diverge.
%j The day of the year as a decimal number (001-366).
%m The month as a decimal number (01-12).
%n A newline character.
%Q The quarter as a decimal number (1-4).
%t A tab character.
%U The week number of the year (Sunday as the first day of the week) as a decimal number (00-53).
%u The weekday (Monday as the first day of the week) as a decimal number (1-7).
%V The ISO 8601 week number of the year (Monday as the first day of the week) as a decimal number (01-53). If the week containing January 1 has four or more days in the new year, then it is week 1; otherwise it is week 53 of the previous year, and the next week is week 1.
%W The week number of the year (Monday as the first day of the week) as a decimal number (00-53).
%w The weekday (Sunday as the first day of the week) as a decimal number (0-6).
%x The date representation in MM/DD/YY format.
%Y The year with century as a decimal number.
%y The year without century as a decimal number (00-99), with an optional leading zero. Can be mixed with %C. If %C is not specified, years 00-68 are 2000s, while years 69-99 are 1900s.
%E4Y Four-character years (0001 ... 9999). Note that %Y produces as many characters as it takes to fully render the year.
Related
Using tableau, I am trying to analyze data on a weekly basis but with some modifications.
I want the first week of any given month to end on a Saturday with a minimum of one week.
Middle weeks are 7 days long (Sunday to Saturday).
The last week of a month Should be from Sunday to the last day of the month.
This question is very similar to the solution of this question but with minor differences: https://community.tableau.com/thread/230894
Here is an example for April
Week 1 has April 1 start date
Week 2 has April 12 start date
Week 3 has April 19 start date
Week 4 has April 26 start date
This seems to work:
IF DAY([Update Time])<[ISO Time]
THEN IF [ISO Time] <=6
THEN DATEADD('day',7-[ISO Time],[Update Time])
ELSE DATEADD('day', 7-[ISO Time],[Update Time])
END
ELSE IF [ISO Time]<=6
THEN DATEADD('day',-[ISO Time],[Update Time])
ELSE DATEADD('day',7-[ISO Time],[Update Time])
END
END
It's commonplace even outside of software to communicate time or date intervals in a truncated manner. For example: 1h10m translates to "One hour and ten minutes."
This could be abstracted to a set of rules. For instance: A date interval is represented as a combination of _h, _m, (and so on), where _ characters represent non-negative integers or floats, which are summed into one date interval object.
Mixing days, hours, minutes are allowed. For example, 0.5d1h60m would be a synonym for 14h.
Is there a standard defined out there anywhere that resembles this?
The standard for this is a Duration, defined by ISO 8601.
Note that an Interval is a different concept (also defined by the same ISO), although both are closely related:
A Duration defines an amount of time (like "1 hour and 10 minutes" or "2 years, 3 months and 4 days"). But it doesn't tell you when it starts or ends ("1 hours and 10 minutes" relative to what?). It's just the amount of time, by itself.
An Interval (quoting wikipedia) is "the intervening time between two time points". It has a defined start and end dates, but you can use a Duration to define it, as it can have 4 different formats:
Start and end, such as 2007-03-01T13:00:00Z/2008-05-11T15:30:00Z
Start and duration, such as 2007-03-01T13:00:00Z/P1Y2M10DT2H30M
Duration and end, such as P1Y2M10DT2H30M/2008-05-11T15:30:00Z
Duration only, such as P1Y2M10DT2H30M, with additional context information
Cases 1, 2 and 3 are equivalent (all have the same start and end dates). The only difference is that in cases 2 and 3, the duration P1Y2M10DT2H30M is used to calculate the other date (in case 2, you add it to the start date, and in case 3 you subtract it from the end date).
As you can notice above, the standard format for a Duration is P[n]Y[n]M[n]DT[n]H[n]M[n]S, where:
P is the duration designator (for period) placed at the start of the duration representation.
Y is the year designator that follows the value for the number of years.
M is the month designator that follows the value for the number of months.
W is the week designator that follows the value for the number of weeks.
D is the day designator that follows the value for the number of days.
T is the time designator that precedes the time components of the representation.
H is the hour designator that follows the value for the number of hours.
M is the minute designator that follows the value for the number of minutes.
S is the second designator that follows the value for the number of seconds.
So, "1 year and 10 months" is represented as P1Y10M and "1 hour and 10 minutes" is PT1H10M (note that the T is required to resolve the potencial ambiguity between 1 month (P1M) and 1 minute (PT1M), as they use the same letter M as designator).
As #MattJohnson commented, the math with dates it's not always obvious, so the equivalence between different durations can't be what we normally expect.
For the examples below, I'm using Java 8 (just to show how durations can be tricky). Note that the java.time API uses 2 different classes (Period and Duration), but the idea for both is the same (they're both amounts of time).
A duration of 1 month is equivalent to how many days? It depends:
// one month period
Period oneMonth = Period.parse("P1M");
// January 1st
LocalDate jan = LocalDate.of(2016, 1, 1);
System.out.println(jan); // 2016-01-01
// January 1st plus 1 month period = February 1st
LocalDate feb = jan.plus(oneMonth);
System.out.println(feb); // 2016-02-01
// February 1st plus 1 month period = March 1st
LocalDate mar = feb.plus(oneMonth);
System.out.println(mar); // 2016-03-01
// difference between Jan 1st and Feb 1st = 31 days
System.out.println(ChronoUnit.DAYS.between(jan, feb)); // 31
// difference between Feb 1st and Mar 1st = 29 days (2016 is leap year)
System.out.println(ChronoUnit.DAYS.between(feb, mar)); // 29
So, adding 1 month to January 1st results in February 1st - in this case, 1 month is equivalent 31 days (A.K.A. adding a 1 month duration (P1M) is equivalent to adding a 31 days duration (P31D)), and adding 1 month to February 1st results in March 1st (in this case, 1 month = 29 days, because 2016 is a leap year).
1 day = 24 hours? Not always. If there's a Daylight Saving Time shift involved, you can get strange results:
// 1 day period
Period oneDay = Period.parse("P1D");
// 24 hours period
Duration twentyFourHours = Duration.parse("PT24H");
// in Sao Paulo, summer time starts at Oct 15, at midnight
// getting a date one day before DST change, at 10:00 AM
ZonedDateTime z = ZonedDateTime.of(2017, 10, 14, 10, 0, 0, 0, ZoneId.of("America/Sao_Paulo"));
System.out.println(z); // 2017-10-14T10:00-03:00[America/Sao_Paulo]
// add 1 day - gets the same hour (10:00 AM)
System.out.println(z.plus(oneDay)); // 2017-10-15T10:00-02:00[America/Sao_Paulo]
// add 24 hours - gets 11:00 AM because of DST shift (at midnight, clocks moved forward 1 hour)
System.out.println(z.plus(twentyFourHours)); // 2017-10-15T11:00-02:00[America/Sao_Paulo]
In São Paulo, at October 15th, 2017, DST starts (clocks are moved forward by 1 hour), so:
If you add 24 hours to October 14th at 10 AM, you'll get October 15th at 11 AM
But if you add 1 day, you'll get October 15th at 10 AM
So, in this case, 1 day = 23 hours - it means that adding a 1 day duration (P1D) is equivalent to adding a 23 hours duration (PT23H)
When DST ends, is the opposite: clocks move back 1 hour, and 1 day will be equivalent to 25 hours.
So, the standard defines the format and meaning of the amounts of time concepts, but the equivalence between different durations will depend on the context (although it might sound non-intuitive that 1 day is not always 24 hours, but date/time math is not as obvious as we'd like).
You can use moment: http://momentjs.com/docs/#/durations/
moment.duration(100); // 100 milliseconds
moment.duration(60000).humanize(); // a minute
Read more in the above linked docs. And to get all unit values you may want to use the ISO8601 Format:
moment.duration(1, 'd').toISOString() // "P1D"
For example, "P3Y6M4DT12H30M5S" represents a duration of "three years, six months, four days, twelve hours, thirty minutes, and five seconds".
Read more directly under http://momentjs.com/docs/#/durations/as-iso-string/
The code below gives a decimal day for one specific year.
HolidayArrayDate(2) = datenum(2012,01,16,00,00,00); %MartinLutherKingJrBirthday
I am trying to make the holiday more general for an input "dataYear" instead of specifying it as "2012". Martin Luther King Jr Birthday is the third Monday of ever year. When i provide it an input of any year 2010/2011/2012/2013/2014 through "dataYear", it should automatically choose the third Monday in January for me. How would i dot this?
Thank you!
Starting from the first day of the year, 21 days always suffice to find the third Monday. So: get serial date number for first day of the year (with datenum); get day-of-the-week for that and the following 20 days (datestr(..., 'd')); find the first three Mondays (find(...=='M', 3); and finally pick the third one and convert it into date string (datestr):
dataYear = 2012; %// input
f = datenum(dataYear,1,1); %// 1st day of year, in serial date number format
r = find(datestr(f+(0:20), 'd')=='M', 3); %// find three Mondays from that day on
result = datestr(f+r(3)-1); %// third Monday, in date string format
When run these two commands in Matlab command line:
dateNumber = datenum('20130101', 'yyyymmdd');
dateString = datestr(dateNumber, 'yyyymmdd')
I got
dateString = 14700101
I suspect that it is a confusion between Buddhist year and Christian year because 2013-1470 == 543 (Buddhist year started in counting 543 years before Christian year). In other words, the datenum function interpreted 2013 as Buddhist year and convert it to a date number representing Christian year, 1470, but datestr function did not convert it back to Buddhsit year.
How can I configure the datenum function so that it understands 2013 as a Christian year?
What is the difference between "%X" and "%x" in following the functions?!
(defvar insert-time-format "%X"
"*Format for \\[insert-time] (c.f. 'format-time-string').")
-----------
(defvar insert-date-format "%x"
"*Format for \\[insert-date] (c.f. 'format-time-string').")
Obvious, if you see the description for insert-time-format you will see that:
%x is the locale's "preferred" date format.
%X is the locale's "preferred" time format.
%x inserts the time.
%X inserts the date.
You could probably take a pretty good guess at the difference based on the variable names insert-time-format and insert-date-format, however your first port of call after that should be the help for the format-time-string function which is referred to in the help for both of those variables:
C-hf format-time-string RET
format-time-string is a built-in function in `C source code'.
(format-time-string FORMAT-STRING &optional TIME UNIVERSAL)
Use FORMAT-STRING to format the time TIME, or now if omitted.
TIME is specified as (HIGH LOW . IGNORED), as returned by
`current-time' or `file-attributes'. The obsolete form (HIGH . LOW)
is also still accepted.
The third, optional, argument UNIVERSAL, if non-nil, means describe TIME
as Universal Time; nil means describe TIME in the local time zone.
The value is a copy of FORMAT-STRING, but with certain constructs replaced
by text that describes the specified date and time in TIME:
%Y is the year, %y within the century, %C the century.
%G is the year corresponding to the ISO week, %g within the century.
%m is the numeric month.
%b and %h are the locale's abbreviated month name, %B the full name.
%d is the day of the month, zero-padded, %e is blank-padded.
%u is the numeric day of week from 1 (Monday) to 7, %w from 0 (Sunday) to 6.
%a is the locale's abbreviated name of the day of week, %A the full name.
%U is the week number starting on Sunday, %W starting on Monday,
%V according to ISO 8601.
%j is the day of the year.
%H is the hour on a 24-hour clock, %I is on a 12-hour clock, %k is like %H
only blank-padded, %l is like %I blank-padded.
%p is the locale's equivalent of either AM or PM.
%M is the minute.
%S is the second.
%N is the nanosecond, %6N the microsecond, %3N the millisecond, etc.
%Z is the time zone name, %z is the numeric form.
%s is the number of seconds since 1970-01-01 00:00:00 +0000.
%c is the locale's date and time format.
%x is the locale's "preferred" date format.
%D is like "%m/%d/%y".
%R is like "%H:%M", %T is like "%H:%M:%S", %r is like "%I:%M:%S %p".
%X is the locale's "preferred" time format.
Finally, %n is a newline, %t is a tab, %% is a literal %.
Certain flags and modifiers are available with some format controls.
The flags are `_', `-', `^' and `#'. For certain characters X,
%_X is like %X, but padded with blanks; %-X is like %X,
but without padding. %^X is like %X, but with all textual
characters up-cased; %#X is like %X, but with letter-case of
all textual characters reversed.
%NX (where N stands for an integer) is like %X,
but takes up at least N (a number) positions.
The modifiers are `E' and `O'. For certain characters X,
%EX is a locale's alternative version of %X;
%OX is like %X, but uses the locale's number symbols.
For example, to produce full ISO 8601 format, use "%Y-%m-%dT%T%z".
%x formats the input to hex. The difference between %x and %X is that the letters are written in upper case.
E.g.
%x, 15 will be f
%X, 15 will be F