Questions about Mathematica's date and time functions.

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37
votes
1answer
744 views

How can I manipulate TemporalData?

Version 9 introduced TemporalData but, truth be told, the documentation doesn't suggest that one can do much with it. Many of us have probably assumed we'd be ...
24
votes
0answers
561 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 ...
23
votes
6answers
1k views

Faster alternatives for DayOfWeek

It has been noticed on several occasions that DayOfWeek function is rather slow when applied to a large list of dates, e.g. in this recent question. What faster ...
20
votes
3answers
821 views

Does Mathematica have a built-in date picker?

Does Mathematica have an interactive date input control that lets the user choose a date by browsing to a calendar view and returning the selected date as a date list? For example, something like the ...
19
votes
3answers
1k views

How can I make a heatmap of a days in year?

I know Mathematica has a ListPlot for time series but does it have a function for visualizing a list of dates as a heat map like this: This idea is from D3, check it out here.
17
votes
1answer
926 views

The Orbit and Perigee of the Flamsteed comet

Historical context This year we have the 330-th anniversary of the Battle of Vienna - one of the great formative events of European history, it took place on September 12, 1683. Kara Mustafa, Grand ...
16
votes
9answers
1k views

Determining the week of a year from a given date

Consider the following: AbsoluteTime["17/04/2012",{"Day","/","Month","Year"}]; From my calendar in my office, I know that April 17th is in the 16th week of the ...
12
votes
2answers
347 views

How is AstronomicalData interpreting its date arguments?

It is easy to confirm that the AstronomicalData is not interpreting its arguments as UTC (or "GMT", which is, in any case, ambiguous) dates by verifying that the ...
12
votes
1answer
220 views

Is there a way to get AbsoluteTime to correctly report absolute time differences?

Absolute time supposedly reports the "total number of seconds" between two dates, but it does not. For example because of the leap second applied at 2012-06-30T23:59:60Z ...
11
votes
5answers
800 views

Sort date list in format DD/MM/YYYY

I have a list of dates (ranging from 2007 to 2012) in the DD/MM/YYYY format and I need to sort this list. My problem is, when I simply use Sort[] I get: ...
11
votes
2answers
880 views

How do I compute sidereal time and JD?

There was once a package that provided a wide range of functions for computing astronomical information. This package now appears to be out of date; but as near as I can tell, many of the useful ...
11
votes
3answers
508 views

Simpler way to fill date gaps with zero values

One basic problem when working with data like sales and dates is the case where you dont't have sales in all days, so you have to fill it to take information as average or to make a plot. See this toy ...
11
votes
3answers
261 views

Does Mathematica support importing ISO 8601 date strings?

Does Mathematica have a built-in function to convert ISO 8601 formatted date strings (e.g. 2012-01-04T00:00:00) to a date list? ISO 8601 strings come in a variety ...
10
votes
7answers
210 views

DateList coupled with String Operations

Through some webscraping, I have the following list: ...
10
votes
2answers
260 views

Approaches For Creating Cycle Plots in Mathematica

I am trying to create a cycle plot in Mathematica, and I am having a hard time finding the right approach to create the visualization. Can anyone give me a few pointers as to how to approach the ...
10
votes
2answers
435 views

MovingAverage[] and Fit[] with data containing DateLists

I have data which has the following appearance: data = {{DateList, Real}, ..., {DateList, Real}} It's easy to visualize the data by using ...
10
votes
1answer
439 views

How to import date (YYYY-MM-DD) data from a file?

I have a file with data in form {date, value}: 2010-05-19 17 2010-05-20 20 ...
10
votes
1answer
183 views

Why do DateList, DateString, and AstronomicalData ignore $TimeZone?

My reading of the documentation for DateList and DateString lead me to believe that both functions use ...
9
votes
1answer
193 views

How can I convert the dates returned by FinancialData into decimal representation?

I'm trying to run a regression using Fit on the output of FinancialData["SPY", "Jan. 1, 2011"]. However, the dates returned ...
9
votes
1answer
293 views

How can I get the frame ticks from DateListPlot?

DateListPlot very nicely chooses major and minor frame tick and frame tick label/markers. I am building a custom graphics function where either the ...
9
votes
1answer
235 views

How do I determine astronomical transit times?

Mathematica, through the "legacy" Scientific Astronomer package, used to have the ability to easily determine accurate transit times of astronomical objects simply, with ...
9
votes
1answer
111 views

DateList not using current year when a year is not specified

According to the documentation when using DateList but not giving it a year it should use the current year. It is not doing that for me. Instead it uses 1900. ...
8
votes
3answers
296 views

Faster Alternatives to DateDifference

I need a faster implementation of FractionOfYear and FractionOfMonth, which do the following: Input: A time/date specified by ...
8
votes
1answer
215 views

Day of the week vs time on BoxWhiskerChart

I am completely stuck on how to approach this problem: I'm basically trying to figure out when is the best time to tweet on twitter, based on a list of timestamps: Here are the raw values: ...
7
votes
3answers
385 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; ...
7
votes
1answer
181 views

ScheduledTask with scoped variables. Working with timed evaluation

I guess I have to try harder and focus more but timed evaluation always frustrates me. I will show the issue on simple example of delayed trigger. ...
7
votes
3answers
302 views

Find all the last weekends in a year

In order to obtain the weekends of a year you'd use something like this: ...
7
votes
2answers
136 views

DatePlus and DateList are inconsistent with numerical handling of the final element

If you run this code you will see that DatePlus and DateList are inconsistent in the format of the lowest order element of the ...
6
votes
6answers
380 views

Sort list by day names (Monday, Tuesday, etc)

I have some dates in a list, and I want to plot how many of those dates are Monday, Tuesday, etc. I'm using this: data = {...} Tally[DayOfWeek /@ data] and I ...
6
votes
3answers
441 views

Friday the 13th related tables

This code ...
6
votes
3answers
225 views

Importing and manipulating strings - time data

I have a list of time durations, which are strings of the form: "hh:mm:ss". Here's a sample for you to play with: ...
6
votes
2answers
184 views

DateList Segmentation of data

I've been trying to separate large segments of DateList formatted data (years worth at a time) into individual days using the Split function. The data has the form: ...
6
votes
2answers
188 views

How can this AbsoluteTime call be made faster?

I need to convert tons of date strings into absolute times. This generates an example data set of 10,000 strings: ...
6
votes
3answers
243 views

Determining the dates of days

I'm trying to use WeatherData[] to give me (not sure how) the temperature, humidity, wind-speed, cloud cover... at a certain location. I only want the information ...
6
votes
5answers
317 views

Handling holidays in financial time series

I have two lists: list1and list2, which are financial time series with only 2 variables—date and price. The problem is: these ...
6
votes
2answers
483 views

Select elements of list within a date range

I have a list which consists of elements each of which has a date in DateList format, a number and a flag (Y/N). e.g. ...
5
votes
2answers
699 views

Measuring execution time of code

How one can measure the execution time (time that is spent for code to finish) of a program in Mathematica? I understand that there are general timing functions (Timing, AbsoluteTiming, TimeUsed, ...
5
votes
2answers
483 views

Finding the intersection of two date lists

I've got two lists that look like this ...
5
votes
4answers
370 views

How to Merge Date and Time?

Given the following time series data where row is date and column is time intervals. ...
5
votes
2answers
366 views

From a list of dates get a list of the last date available in a each month

I wondered if anyone has another or even a more direct way of finding the last dates of each month available from a list of successive dates? I currently do the following (note: nothing special about ...
5
votes
2answers
121 views

How can AbsoluteTimes be split by date faster?

I have data where the date is stored as an AbsoluteTime. Here's a dummy dataset: ...
5
votes
3answers
166 views

DateList's aggressive interpretation of TimeML duration codes

DateList "aggressively" interprets strings, such as "p72h": DateList["p72h"] gives ...
5
votes
1answer
104 views

Why DateDifference returns machine number?

Is there any specific reason why DateDifference cannot give an exact number in this case? ...
4
votes
2answers
133 views

How to change start and end date of DateListPlot with Manipulate?

Let's say I have a one dimension list d with length L. The $x$-axis in the plot starts from ...
4
votes
1answer
52 views

Poor (network) performance of Interpreter[“Time”]

I was surprised to see that Interpreter requires external WR resources as this is not documented, at least not here. On a 3Ghz iMac, took ~half a minute to ...
4
votes
1answer
464 views

Simple countdown timer in Mathematica

I dug around a bit and did not find a simple and clear implementation of countdown stopwatch in Mathematica. I am looking for a function that takes as an input a certain integer and then counts down ...
4
votes
2answers
221 views

Can Mathematica understand Excel dates when in number format?

I have a very large Excel file with dates in the format 2013/01/17 08:02:00 PM which is a custom date format. I have to convert this file to CSV in order to import it into Mathematica because I can't ...
4
votes
1answer
111 views

Strange behavior of DateList when converting string

DateList experiences some strange behavior which i cannot explain. This code works fine: ...
4
votes
1answer
276 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 ...
4
votes
1answer
155 views

Is DateString supposed to be truncating seconds?

If I configure DateString to format dates as ISO dates with ...