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algorithm - How can I extend BinCounts to work on Times and Dates?


I want to extend BinCounts to work on a list of times or dates, binning them by Day, Week, Hour of the Month, Day of the Year, etc... So given a list of times and a time bin spec, I need to calculate the bin counts.


One example might be if I have list of times I've been on Facebook and I want to to plot these times on a 2D Histogram where the Y axis is "MinuteOfTheDay" and the x axis is "DayOfTheWeek". Alpha can already do this (but not with arbitrary time bins)


enter image description here


To clarify my question I made a prototype:


d = RandomDates[1000];
Timing[TimeBinCounts[d, {"Day", "Week"}]]

gives the proper counts {157, 150, 136, 147, 149, 129, 132}, (e.g. Count[DayOfWeek /@ d, Monday] == 157). And queries like


Timing[TimeBinCounts[d, {"Month", "Year"}]]


work too, but I'm not sure how to handle an arbitrary time bin spec like "HoursOfTheWeek"


Timing[TimeBinCounts[d, {"Hour", "Week"}]]

Will not work...


<TimeBinCounts::badspec = "The time bin spec `1` is not acceptable.";
DaysOfTheWeek = {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday};
daysNum = Thread[Rule[DaysOfTheWeek, Range[7]]];
RandomDateList[] := {RandomInteger[{1800, 2100}], RandomInteger[{1, 12}], RandomInteger[{1, 28}], RandomInteger[{0, 23}], RandomInteger[{0, 59}], RandomInteger[{0, 59}]};

RandomDates[n_] := Table[RandomDateList[],{n}]

TimeSpecHelper[spec_] := Module[
    {types, convert, result},
    types = {"Second", "Minute", "Hour", "Day", "Week", "Month", "Year"};
    convert = {60, 60, 24, 7, 4.345, 12};
    result = Range[Times @@ Part[convert, Most[Range @@ Flatten[
        First[Position[types, #]]& /@ spec]]]];
    If[MatchQ[spec[[1]], "Second"|"Minute"|"Hour"],
        result - 1,

        result
    ]
]

TimeBinCounts[times_List, spec_] := Module[
    {dayorder, bins, minDate, maxDate, order},

    minDate = Min[times[[All, 1]]];
    maxDate = Max[times[[All, 1]]];


    order = Thread[Rule[{"Second", "Minute", "Hour", "Day", "Week", "Month", "Year"}, Range[7]]];
    If[Greater @@ (spec /. order),
        Message[TimeBinCounts::badspec, spec];
        Return[$Failed];
    ];

    Switch[spec,
    {"Day","Week"} | "Day",
        With[{days = DayOfWeek /@ times /. daysNum},
        BinCounts[days, {1, 8, 1}]],

    {"Hour", "Day"}|"Hour",
        BinCounts[times[[All, 4]], {0, 24, 1}],
    {"Day", "Month"},
        BinCounts[times[[All, 3]], {1, 32, 1}],
    {"Month", "Year"}|"Month",
        BinCounts[times[[All, 2]], {1, 13, 1}],
    "Year",
        With[{interval = Range[minDate[[1]], maxDate[[1]]]},
            Count[times[[All, 1]], #]& /@ interval
        ],

    _,  
        order = Thread[Rule[{"Second", "Minute", "Hour", "Day", "Month", "Year"}, 
            Range[6]]];
        With[{interval = TimeSpecHelper[spec]},
            Count[Mod[times[[All, 6 - (spec[[1]] /. order) + 1]], Length[interval]], #]& /@ TimeSpecHelper[spec]
    ]
]
]


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