Questions about Mathematica's date and time functions.

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4
votes
2answers
131 views

Is it safe to change the value of $TimeZone?

I'd like to configure some of my notebooks to assume all calculations using dates, times and locations (notably AstronomicalData , but others too) take place at the ...
2
votes
1answer
24 views
2
votes
3answers
168 views

Delete rows based on specific periods

I have data (.xlsx format): two columns - data in first column imported as DateObject (dates with specific time), data in second column are numbers (113388.28, 865165.98 etc.). I want to delete the ...
4
votes
3answers
193 views
0
votes
1answer
86 views

How to make a cumulative time plot?

So I'm working with this data set where there is just one input(a date and time) per line in a .csv file. I've let Mathematica understand the input using "DateStringFormat". The time looks like ...
4
votes
2answers
115 views

Problem About TimelinePlot

I have some data from wikipedia. ...
3
votes
0answers
104 views
2
votes
0answers
59 views
4
votes
1answer
103 views

Problems with TimelinePlot

I'm trying to play with the example in this recent blog post, but I'm having a few basic issues with TimelinePlot: Labels are getting cut off: How can I get ...
0
votes
0answers
57 views

Improving semantic interpretation of dates

SemanticInterpretation and Interpreter are promising but imperfect, eg extracting dates and calendar expressions from ...
1
vote
4answers
115 views
5
votes
1answer
57 views

DateObject for current date skips a day when crossing the date line with TimeZone

The DateObject was introduced in version 10 of Mathematica. One can call it to fetch the current local date and time: ...
2
votes
3answers
91 views

Converting timestamps into a decimal in minutes

I am importing a list of timestamps (hour:minutes:seconds) from a series of text files. I have the list: ...
29
votes
1answer
759 views

What calendar is Mathematica using for dates in the distant past?

It appears that Mathematica treats all dates as proleptic Gregorian dates by default, a hypothesis that can be easily tested by using AbsoluteTime to compute the ...
5
votes
1answer
85 views

Handy dates conversion

I feel like something very basic is missing me, $dateformat = {"Year", "Month", "Day", "Hour"}; date = DateString[$dateformat] DateString["Date"] ...
6
votes
2answers
112 views

SetOptions for CoordinatesToolOptions for DateListPlot?

Bug introduced in 10.0 and persisting through 10.1.0 or later DateListPlot does not respect my Options setting for ...
0
votes
0answers
37 views

Speeding up a “filling in” process

I have a sparse EventSeries that looks something like ...
4
votes
3answers
182 views
5
votes
4answers
194 views
4
votes
3answers
157 views

Converting between AbsoluteTime and Unix time

By trial and error, I've found that the following gives the current Unix time: AbsoluteTime[] - UPOCH where UPOCH can be defined in any of the following ways: ...
1
vote
2answers
167 views

Extract data from DateListPlot, limited by PlotRange

Extracting the points from a line in a ListPlot in this answer uses points = Cases[Normal@plot, Line[pts_] :> pts, Infinity]; This works in DateListPlot ...
0
votes
1answer
66 views
1
vote
3answers
156 views

How to calculate time period?

I have the starting and ending dates and times. And I need to calculate the night time in this period (from 10 pm (22) to 6 am (6)). Example: starting date and time is {2015, 1, 4, 3, 10} ending date ...
1
vote
1answer
43 views

Convert Dates to values on an X axis

I have a bunch of dates and values which I put into the DateListPlot to get a graph. However I would also like to put this information into the Fit or LeastSquares to estimate what the value would be ...
5
votes
1answer
85 views

How to remove the TimeZone from a TimeObject

TimeObject constructor adds TimeZone even when it's not meaningful or appropriate. In this example, Mathematica imputes ...
14
votes
3answers
269 views

Min, Max are slow on TimeObjects

fixed in 10.1 (windows) There's something wrong with how Min and Max are implemented for ...
3
votes
2answers
64 views

Make a time IntervalSlider

I want to make a time interval slider with an initial setting of (10:00:00 Mar. 8 2015, 12:30:00 Mar. 8 2015) and which varies from 00:00:00 Mar. 8 2015 to 22:30:00 Mar. 8 2015 with a granularity of ...
4
votes
2answers
2k views

No weekends please

I need to get the DateValues of the last 30 days (starting from yesterday, not today!) excluding saturdays and sundays. I want that the dates are german time (GMT ...
8
votes
2answers
676 views

UNIX time to DateList

I have data that is timestamped with UNIX time, which is the number of seconds since January 1, 1970 UTC. Unfortunately, it seems that most of the date and time functions in Mathematica are based on ...
2
votes
1answer
46 views

DateValue returns inconsistent types

More of a 'why' than a 'how' question... DateValue[{2014,4,12},"DayName"] returns Saturday, a symbol rather than the string "Saturday". Every other result that ...
1
vote
0answers
45 views

DateObject from AbsoluteTime broken

In the middle of a session (10.0.2 / Win64 / 2.7Gb working set - peak was over 7Gb) the form/definition for DateObject from an integer has disappeared. ...
1
vote
1answer
43 views

How to change time zone for all outputs? [closed]

How to change the time zone in Mathematica for all functions returning a date or time?
1
vote
1answer
43 views

Change date format in nested lists

I have a list of index symbols and data as follows: ...
7
votes
4answers
475 views

Filter list based on date

What I would like to do is remove entries from a list of instrument data when it is in maintenance. The maintenance data I have is a series of dates which look like this; ...
3
votes
2answers
98 views

AbsoluteTime parse two different date formats

I have a series of dates that regularly change format (24 hrs/12 hrs). Is there an easy way to parse this data? ...
3
votes
2answers
186 views

Time Zone Conversion

I use Mathematica to administer my share depots. The depots contain shares of many different time zones. I update the depot values several times a day. My problem is that Sidney, Australia, (it might ...
1
vote
1answer
98 views

How to plot multiple yearly data in one graph

There is a dataset: for each year a single data for 6 seas. I would like to have a graph to visualize paralel changes. This is what I attempted to reproduce ...
1
vote
0answers
50 views

Is Daylight Savings Time accounted for when using AbsoluteTime[]? [closed]

I have been running rather long computations lately and timing them using AbsoluteTime[] by calling it at the start and end of the computation. ...
1
vote
0answers
31 views

Expose TimeObject fractions of a second and user-defined formatting

The default TimeObject formats (doc page), don't display fractions of seconds: ...
4
votes
1answer
72 views

EasterSunday replacement in Mathematica 10

The Calendar package, now obsolete, had functionality for "special dates", in particular EasterSunday[]. The documentation says it's been subsumed into Wolfram ...
4
votes
0answers
80 views

Is it possible to specify GMT as default in OpenSQLConnection or JDBC?

I'm connecting to a PostgreSQL database, with tables containing TIMESTAMPs with timezone, using ...
1
vote
1answer
48 views

How to convert a string representing date into a DateList expression?

How to convert a string representing date into a DateList expression? For example, how to turn "1/2/2000" into {2000,1,2} assuming American style, and {2000, 2, 1} assuming European style, ...
3
votes
0answers
55 views

How can I set up a cell style that is ascending dates?

Outline style notebooks have cell counters that are simply ascending numbers, but what if I want to apply a function to them and have descending dates like this: So that they auto format and the ...
1
vote
2answers
153 views

How do I remove the quotation marks from each element of a list containing dates that I have import from excel?

I've been stuck in this problem for 1 week. I just want to make a graph (Log-Return vs time (in year, month, day)). The code is: ...
1
vote
1answer
135 views

Trace two DateListPlots?

I currently have two DateListPlots in the same graph, with two different y-axes. I downloaded the package "TwoAxisDateListPlot" to accomplish this with ease. Now I want to be able to trace both of the ...
3
votes
3answers
133 views

Get the complement date range

Suppose that I have a date range list drlist = {{"2015-01-01", "2015-01-05"}, {"2015-01-07", "2015-01-07"}, {"2015-01-12", "2015-01-23"}} ...
1
vote
1answer
51 views

Why does TimeSeriesShift is just adding a fixed number of days?

I'd like to shift all contents of a TimeSeries object by one month. By shifting Feb. 1st I would expect to receive Mar. 1st. However it's not the case for Mathematica: ...
4
votes
4answers
195 views

Extract Specific Dates from DateList

Hopefully this is an easy question but I couldn't find an easy answer anyway. Surely there is some simple way to splice this... I want to take a large datelist in the format of {{2014,12,31}, value} ...
5
votes
1answer
90 views

ChineseLunar calendar system mystery

I tried to make a custom holiday calendar for the Korean Stock Exchange. And I found that the built-in "ChineseLunar" calendar system gives me an awkward result. The code is ...
1
vote
1answer
101 views

Plotting CSV files with UTC Universal Time

So I have many CSV files in format like this: 2014-12-11T16:13:13.038337Z , 3.90092 2014-12-11T16:14:13.456558Z , 3.89734 2014-12-11T16:15:12.444318Z , 3.90092 I imported a CSV file ...