Pop-up documentation for "The new function of the day"

Question

The Wolfram Language has more than 5000 built-in functions and constants.

functionslist = Flatten[
   Names[#] & /@ Flatten[
     {# <> "*", "$" <> # <> "*"} &
      /@ CharacterRange["A", "Z"]
     ]
   ];
Length @ functionslist

5689

OK, 5689 have documentation in Mathematica 10.3, to be more precise. In order to keep up with that, I would like to pick randomly a function documentation to refresh.

SystemOpen["paclet:ref/" <> RandomChoice[functionslist]]

But I would like to refresh new functions more often than old ones.

SystemOpen["paclet:guide/SummaryOfNewFeaturesIn103"]

How can we implement a "New function of the day" function that focuses on functions new to the current version?

Bonus if it picks from all functions with decaying probability as a function of "age".

_{Code adapted from this question.}

Answer 1

Here is an alternative procedure using EntityValue[] and Dataset[]. The idea is to build a Dataset[] containing function names and the version numbers they were introduced in, and then use a query to pull all the names that are new in a particular version. One can then pick any of these names randomly. A way to bias newer functions over older ones is to use RandomChoice[] on the list of version numbers, with each version number being its own weight.

$versions = {1, 2, 2.2, 3, 4, 4.1, 4.2, 5, 5.1, 5.2, 6, 7, 8, 9,
             10, 10.1, 10.2, 10.3};

symtable = Dataset[AssociationThread[{"Name", "VersionIntroduced"}, #] & /@
           EntityValue["WolframLanguageSymbol", {"Name", "VersionIntroduced"}]];

randomHelpPage := With[{version = RandomChoice[$versions -> $versions]},
         SystemOpen["paclet:ref/" <> RandomChoice[Normal[
                    symtable[Select[#VersionIntroduced == version &], "Name"]]]]]

Button["Random WL Function", randomHelpPage]

This should now function in a similar manner to Jason's solution.

Answer 2

First we get a list of the functions, indexed by their introduction date. The method suggested by Szabolics turned out to be very slow - although it has the advantage that it gives a date rather than just the year.

And as Kuba mentioned, the functions gathered by Rhermans's function do not all have help pages, so we just grab the file list from the help pages directory.

functiondatelist = Module[{dir, symbolslist, datelist, mmagrep},

   (*
   Here I'm scanning only what is in the 'ReferencePages/
   Symbols' directory, we could add other directories to scan 
   *)
   dir = 
    FileNameJoin@{$InstallationDirectory, "Documentation", "English", 
      "System", "ReferencePages", "Symbols"};
   symbolslist = FileNames@FileNameJoin[{dir, "*"}];
   Print["Found " <> IntegerString@Length@symbolslist <> 
     " symbols with help pages"];
   (*
   Now we scan the notebooks for the phrase "Introduced in" and \
   thereby grep the year it was created.
   *)
   mmagrep[file_, patt_] := 
    With[{data = Import[file, "Lines"]}, 
     Pick[Transpose[{Range[Length[data]], data}], 
      StringFreeQ[data, patt], False]];
   Print["Scanning for introduction dates:"];

   Monitor[
    datelist = 
      Table[StringCases[
          mmagrep[symbolslist[[n]], "Introduced in"][[1, 2]], 
          DigitCharacter ..][[1]] // ToExpression, {n, 
        Length@symbolslist}];
    , n];

   (*Now bin up the list of functions by their year *)

   Reverse@SortBy[
     GatherBy[
      Transpose[{FileBaseName /@ symbolslist, 
        datelist}], #[[2]] &], #[[1, 2]] &]

   ];

The symbol-introduction years aren't evenly distributed,

DeleteDuplicates[Flatten@functiondatelist[[All, All, 2]]]

(*  {2015, 2014, 2012, 2010, 2008, 2007, 2005, 2004, 2003, 2002, 2000, 
      1999, 1996, 1993, 1991, 1988} *)

Choose some directory in your $Path where you like to keep packages, and create a folder titled RandomHelp to write this data to. I don't mind having a cluttered home directory so I just use

Export[FileNameJoin[{directoryinyourpath,"RandomHelp", "mma_symbollist.m"}], 
  functiondatelist];

Copy this text either into a text file named init.m inside the RandomHelp directory,

{symbollist, symbolintyears} = 
  Module[{temp}, 
   temp = Import[FileNameJoin[{"RandomHelp", "mma_symbollist.m"}]];
   {temp[[All, All, 1]], 
    DeleteDuplicates[Flatten@temp[[All, All, 2]]]}];

randomintroductionyear := Module[{test, gamma},
   gamma = 0.15;
   test = Length@symbolintyears + 1;
   While[test > Length@symbolintyears,
    test = Ceiling@RandomVariate[ExponentialDistribution[gamma]];
    ];
   test
   ];

randomnewhelppage :=
  Module[{year, symbol},
   year = randomintroductionyear;
   SystemOpen[
    "paclet:ref/" <> 
     symbollist[[year, RandomInteger[{1, Length@symbollist[[year]]}]]]]

   ];

Button["Procrastination Button", randomnewhelppage]

If you want to increase the bias towards the new, simply make the gamma value larger. Here I have gamma set to 0.15 and 0.5, respectively

Save the init.m file, and now all you have to do is type

<< "RandomHelp`"

and you get a nice button