# Tag Info

48

The short answer is, yes! There is a whole undocumented package TemporalData containing some useful functions. The results below are from my own spelunking. Feel free to add/amend as appropriate. Let's set up some simple TemporalData objects to explore them: fakedata = Transpose@{DatePlus[{2001, 1}, {#, "Month"}] & /@ Range[0, 99], ...

34

Date-picker implementation in Mathematica The following is my implementation of a simple date-picker. The current date is highlighted in LightBlue and the weekends are highlighted in LightGreen. The selected date is always highlighted in LightRed (the default selection is the current date). You can tap into this calendar by using the Dynamic values for ...

34

It took me quite a while, but finally, here's a visualization of the perigee of Flamsteed's comet: I should first note two things: first, some of the needed data for computing the orbit of comet C/1683 O1 was missing in AstronomicalData["CometC1683O1", "Properties"], and I had to pull information from external sources to supplement the information ...

24

Just a literal implementation of a formula for the day of the week: Clear[dow]; dow[{year_, month_, day_, _ : 0, _ : 0, _ : 0}] := Module[{Y = If[month == 1 || month == 2, year - 1, year], m = Mod[month + 9, 12] + 1, y, c, s = {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}}, y = Mod[Y, 100]; c = Quotient[Y, 100]; s[[...

22

I will provide one solution which will be using Java and a simple Java reloader I recently introduced. This solution brings to the table up to 100-fold speed-up for large lists of dates. Preparation I will borrow @Mike's functions to generate a random list of dates, from his code in his recent question RandomDateList[] := { RandomInteger[{1800, 2100}], ...

20

This question might be considered a duplicate. It is closely related to these: Considerations when determining efficiency of Mathematica code Difference between AbsoluteTiming and Timing Benchmarking expressions Profiling from Mathematica However, one simple reading of this question that I do not believe is covered in the answers above is answered with ...

19

I tried to do something similar a few months ago The easiest way is to write several functions: EventFrame function creates event lables EventFrame[str_, {date_, height_}, OptionsPattern[FontSize -> 14]] := Graphics[{ Black, Thick, Line[{{date, height}, {date, 0}}], Text[Framed[Style[str, FontSize -> OptionValue[FontSize]], {Background -&...

18

This site has exactly what you want here, already in Mathematica code. One example here:

17

Since I'm living in Europe I'm sticking to the European definition of week number which is equivalent to the ISO standard. According to this standard, a week starts on Monday and the first week is the week containing 4 January. Taking this into account you could do therefore do something like weekNumberISO[date_] := Module[{day0, year}, With[{days = {"Mon"...

16

You can use DateDifference to find the time between January 1st and April 17th: DateDifference["Jan. 1", "April 17", "Week"] (* {15.2857, "Week"} *) If you want the "week number" as you've put it, you can just do: Ceiling@First@DateDifference["Jan. 1", "April 17", "Week"] which gives 16. Edit based on Szabolcs's comment: To ensure this works for Jan ...

16

The format specification for DateList is pretty flexible. Since we know that we have <h3> tags wrapped around things, we can just account for them: DateList[{#, {"<h3>", "MonthName", "Day", ",", "Year", "</h3>"}}] & /@ Flatten[dates] (* ==> {{2001, 1, 18, 0, 0, 0.}, {2001, 2, 1, 0, 0, 0.}, {2001, 2, 2, 0, 0, 0.}, {2001, 2, 24,...

16

The reason for the result of DateDifference[{2015, 4, 1}, {2015, 10, 1}, "Year"] (* Quantity[0.5, "Years"] *) is that 2016 is a leap year, so there are 366 days in the year between {2015, 4, 1} and {2016, 4, 1}. Therefore we get 183/366 or exactly 1/2 back. Note also the documented DayCountConvention option, DateDifference[{2015, 4, 1}, {2015, 10, 1}, "...

13

Import[(* file *), "Table", "DateStringFormat" -> {"Year", "-", "Month", "-", "Day"}] seems to work... As a test: Export["test.dat", {{"2010-05-19", 17}, {"2010-05-20", 20}, {"2010-05-21", 19}}, "FieldSeparators" -> " "]; Import["test.dat", "Table", "DateStringFormat" -> {"Year", "-", "Month", "-", "Day"}] {{{2010, 5, 19}, ...

13

Jean Meeus's Astronomical Algorithms (as well as the related book Astronomical FormulĂ¦ for Calculators) is what you should start looking at whenever you need to deal with algorithms for quantities of astronomical interest. For instance, here is a translation of Meeus's method for the Julian Date: Options[jd] = {"Calendar" -> "Gregorian"}; jd[{...

13

There is a built-in DateSetter: {DeveloperDateSetter[Dynamic@date], Dynamic@date} By default the first selectable date is tomorrow and one can only go to future months. However, the option NotebookToolsDateSetterRange can be used to set the first selectable date to sometime in the past, {DeveloperDateSetter[Dynamic@date, NotebookTools...

13

Using Simon's data: In[6]:= datelist = {"29/02/2008", "15/12/2007", "06/09/2007", "06/10/2008", "05/03/2007", "24/01/2010", "19/06/2009", "03/11/2009", "02/02/2010", "25/12/2009"}; We can just sort the data by the absolute time: In[7]:= SortBy[datelist, AbsoluteTime[{#, {"Day", "Month", "Year"}}] &] Out[7]= {"05/03/2007", "06/09/2007", "15/...

13

Here's a TL;DR answer. For more details, follow Mr. Wizard's links. Timing measures the computation time consumed by the kernel process, thus On a 4-core machine, internally parallelized functions such as LinearSolve will show 4-times the Timing, i.e. the sum of CPU time used by each core Pause doesn't use CPU time so it's not included in the Timing. ...

13

For those with v. 10, here's one way. I didn't overlap the bars because it looks nicer this way, imho. schedule[{t1_, t2_}, {t3_, t4_}] := Module[{convert, ts = Flatten[{{t1, t2}, {t3, t4}}, 1][[All, 1]], hours}, convert[{h_, min_}] := h + min/60; hours = Range[Min[ts] - 1, Max[ts] + 1]; NumberLinePlot[{ convert[t1] < x < convert[t2], ...

13

For full ranges There is the function DayRange that can be used for this purpose, but not in the same simple way like CharacterRange. For the days: DayName /@ DayRange[Today, Today ~DatePlus~ {{1, "Week"}, {-1, "Day"}}] {Wednesday, Thursday, Friday, Saturday, Sunday, Monday, Tuesday} For the months: DateValue[#, "MonthName"] & /@ DayRange[Today, ...

13

Another, shorter way is Append[d, t] From the docs, DateObject[date,time] represents the specified date list and TimeObject time. If you need the list you mention in the question, just convert the DateObject using DateList: DateList@Append[d, t] (* {2012, 6, 11, 14, 1, 45.} *)

12

I've shown off Larsen's method before (and see this as well), but here it is as a formal answer: larsen[{yr_Integer, mo_Integer, da_Integer, ___}] := Module[{y = yr, m = mo, d = da, q}, If[m < 3, y--; m += 12]; q = d + 2 m + 1 + Quotient[3 (m + 1), 5] + y + Quotient[y, 4] + Quotient[y, 400] - Quotient[y, 100]; {Sunday, Monday, Tuesday, ...

12

Based on data in Comm ACM. This took a while to only partially automate, largely through a helper function that spreads out the years: diffuse[a_][years_List] := Module[{x0 = 1, x1 = Length[years], y0 = Min[years], y1 = Max[years]}, years // MapIndexed[ {#1, (((y1 - y0)/(x1 - x0))*(First[#2] - x0) + y0) a + (#1) (1 - a)} &]]; ...

12

data = FinancialData["SPY", "Jan. 1, 2011"] /. {d_List, v_} :> {AbsoluteTime@d, v}; model = a x^4 + b x^3 + c x^2 + d x + e; fit = FindFit[data, model, {a, b, c, d, e}, x] modelf = Function[{x}, Evaluate[model /. fit]] Plot[modelf[x], {x, Min@data[[All, 1]], Max@data[[All, 1]]}, Epilog -> Map[Point, data]] Edit Better (tick labels showing dates) ...

12

A simple string-based approach is to swap the order of day/month/year, do the Sort and then swap back again: (* Example data *) datelist = DateString[# + AbsoluteTime[{2007, 01, 01}], {"Day", "/", "Month", "/", "Year"}] & /@ RandomInteger[10^8, 10] {"29/02/2008", "15/12/2007", "06/09/2007", "06/10/2008", "05/03/2007", "24/01/2010", "19/06/...

12

I would do this with rule replacement. First, you want to have a list of the days of the week in the appropriate order: days = DayName@{0, 0, #} & /@ Range[5, 11]; Then, you can take tallied results and turn them into a list of rules: tallied = {{Tuesday, 533}, {Sunday, 487}, {Saturday, 481}, {Friday, 422}, {Thursday, 353}, {Wednesday, 371}}; ...

12

Updated This happens because your DynamicModule returns a dynamic object of which x is passed on to the front-end before the scheduled task starts, so the front-end-x cannot be modified anymore by any process (more details at the end). The problem can be further simplified. This works: RemoveScheduledTask@ScheduledTasks[]; DynamicModule[{x = 0}, ...

12

data = Cases[DayRange[{2000, 1, 1}, {2399, 12, 31}, Friday], {y_, m_, d_} :>d] // Tally // Sort; TableForm[data[[ ;; ;; 2]], TableHeadings -> {None, {"Day", "Number of Fri."}}] (Reverse@SortBy[data, Last])[[;; 5]] {{27, 688}, {20, 688}, {13, 688}, {6, 688}, {25, 687}}

12

This is how you can get the last 30 weekdays starting from yesterday: days = DayRange[DayPlus[Yesterday, -30], Yesterday, "Weekday"] To get {y,m,d} vectors, we might use Take[#, 3] &@*DateList /@ days Regarding the time zone, the only problem I can see would be that Yesterday will not produce the right result around midnight. To check this I used ...

12

For what it's worth, you can monitor the progress of Integrate and NIntegrate. I'm not sure how helpful the tools below are, but I feel it is probably worth mentioning them. Integrate InternalIntegratedebugSwitch If you set InternalIntegrate`debugSwitch to the magic number 10, it will print its (major) steps in searching for the answer. For instance: ...

12

You could inject the value once with a Function instead of With. Cases[RandomInteger[{AbsoluteTime["2001"], AbsoluteTime["2003"]}, 1000], a_ /; a > #] &@ AbsoluteTime["2002"] In V10, we can use named arguments, which is arguably [sic] more readable (and more typing): Cases[RandomInteger[{AbsoluteTime["2001"], AbsoluteTime["2003"]}, 1000],...

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