Re: NotebookGetExpression

[Nowak Robert <Robert.Nowak@XXXXXXX.at>]

Hallo Udo,

danke für dein Interesse am Problem.

Es geht nicht um eine Funktion die sich ihrer Werte entsinnt (geht
übrigens auch mit nicht numerischen Funktionen) sonder darum das sich
ein Notebook sich seiner über "aufwendigere" expression definierter
funktionen erinnert,
also beim erneuten laden des notebooks nach einem neustart des Kernel
ohne das die expression erneut evaluiert werden muss.

Die einfache herangehensweise ist es eine expression zu evaluieren und
dann z.B. mittels copy paste das ergebniss zu kopieren und eine
Funtionsdefinition davorzustellen f[x_]:="PastedEvaluatedExpression" und
weiters die Cell welche evaluiert die expression ergeben hat zu löschen
oder als Evaluatable -> False zu markieren.
Diese Schritte will ich automatisieren.



>> CellPrint[ExpressionCell[Defer[1 + 1], "Input", Evaluatable -> False]]

Hast du eine Idee wie man eine bestehende Cell mit Evaluatable -> False
versieht (natürlich automatisiert, nicht über das Menue)
Habe:
FrontEndTokenExecute[SelectedNotebook[], ...]
vesucht doch in der Doku für CellProperties scheint keine Möglichkeit auf.

LG Robert




On 17.05.2011 22:27, Udo und Susanne Krause wrote:
> Hallo Robert,
>
> es kommt darauf an, welche Art Funktionen benötigt werden:
>
> (i) symbolische Funktionen, dann sagt die Hilfe:
>
> Although := is probably used more often than = in defining functions,
> there is one important case in which you must use = to define a
> function. If you do a calculation, and get an answer in terms of a
> symbolic parameter x, you often want to go on and find results for
> various specific values of x. One way to do this is to use the /.
> operator to apply appropriate rules for x in each case. It is usually
> more convenient, however, to use = to define a function whose argument
> is x.
>
> (ii) numerische Funktionen, dann kann man Funktionen verwenden, die
> sich ihrer Werte entsinnen:
>
> fib[1] = fib[2] = 1;
> fib[n_] := fib[n] = fib[n - 1] + fib[n - 2]
>
> (iii) könnte man ein Package schreiben, das die Funktion myNowak[x_,
> ..., manQ_:False] enthält. Falls manQ nicht spezifiziert wird, müsste
> die Lösung bereits im Package drinstehen und von daher reproduziert
> werden. Falls myNowak[x, ..., True] gerufen wird, darf das package
> selber rechnen.
>
> (iv) A cell that cannot be evaluated:
>
> CellPrint[ExpressionCell[Defer[1 + 1], "Input", Evaluatable -> False]]
>
> Man könnte die bewusste Zelle taggen, sie mit NotebookLocate[] anhand
> des Tags wiederfinden und dann allenfalls mit FrontEndExecute[] die
> Option Evaluatable der Zelle auf False setzen.
>
> Warum kann es nicht die build-in Methode (ii) sein?
> Habe ich die Aufgabe überhaupt verstanden?
>
> Gruss
> Udo.
>
>
>
> On Tue, 17 May 2011 12:09:28 +0200, Nowak Robert
> <Robert.Nowak@XXXXXXX.at> wrote:
>
>> Liebe MMA user vielleicht fällt euch hierzu etwas ein.
>>
>>
>>
>> Dear all !
>>
>> I am looking for a way how to revert to an expensive (processing time)
>> evaluated expression.
>>
>> I would like to have a notebook (or package) containing the expression
>> in question which should be reevaluated only on a manual request and
>> otherwise the once preevaluated expression should be used.
>>
>> Any hints on how this could be achieved simpler ?
>> I found the following solution:
>>
>> (*---------------------------------------------------------------------------------------------------
>>
>> *)
>>
>> (* get the expression of the preceding cell *)
>> NotebookGetExpression[] := Module[{nb, e},
>>        nb = SelectedNotebook[];
>>        SelectionMove[nb, Before, EvaluationCell];
>>        SelectionMove[nb, Previous, CellContents];
>>        e = ToExpression@NotebookRead[nb];
>>        SelectionMove[nb, After, EvaluationCell];
>>        e
>>  ]
>>
>> (* this stands exemplary for an expression expensive to evaluate *)
>> (* after once evaluated the cell will be marked by hand as non
>> evaluatable *)
>> (* would be nice if the non evaluatable marking could be automated *)
>>
>> Expand[(x + y)^2]
>>
>> Out[ ]= x^2 + 2 x y + y^2
>>
>> (* her we get the preceding expression and define a function for it *)
>> Ex[x_, y_] = NotebookGetExpression[];
>>
>> (* test the defined function *)
>> Ex[a, b]
>>
>> Out[ ]= a^2 + 2 a b + b^2
>>
>> (*---------------------------------------------------------------------------------------------------
>>
>> *)
>>
>> (* CellExpression starting here : *)
>> {
>> Cell[BoxData[
>>  RowBox[{
>>  RowBox[{"(*", " ",
>>   RowBox[{
>>   "gets", " ", "the", " ", "expression", " ", "of", " ", "the", " ",
>>    "preceding", " ", "cell"}], " ", "*)"}], "\n",
>>  RowBox[{
>>   RowBox[{"NotebookGetExpression", "[", "]"}], ":=",
>>   RowBox[{"Module", "[",
>>    RowBox[{
>>     RowBox[{"{",
>>      RowBox[{"nb", ",", "e"}], "}"}], ",", "\n", "\t",
>>     RowBox[{
>>      RowBox[{"nb", "=",
>>       RowBox[{"SelectedNotebook", "[", "]"}]}], ";", "\n", "\t",
>>      RowBox[{"SelectionMove", "[",
>>       RowBox[{"nb", ",", "Before", ",", "EvaluationCell"}], "]"}],
>>      ";", "\n", "\t",
>>      RowBox[{"SelectionMove", "[",
>>       RowBox[{"nb", ",", "Previous", ",", "CellContents"}], "]"}],
>>      ";", "\n", "\t",
>>      RowBox[{"e", "=",
>>       RowBox[{"ToExpression", "@",
>>        RowBox[{"NotebookRead", "[", "nb", "]"}]}]}], ";", "\n",
>> "\t",
>>      RowBox[{"SelectionMove", "[",
>>       RowBox[{"nb", ",", "After", ",", "EvaluationCell"}], "]"}],
>>      ";", "\n", "\t", "e"}]}], "\n", "]"}]}]}]], "Input",
>>  CellChangeTimes->{{3.514611168095347*^9, 3.514611328704722*^9}, {
>>   3.5146116455745387`*^9, 3.5146116509185286`*^9}, {
>>   3.514611853377117*^9, 3.5146118571428137`*^9}, {
>>   3.5146120519585495`*^9, 3.514612127927786*^9}, {
>>   3.514612364241467*^9, 3.514612367991467*^9}, {
>>   3.5146124428041286`*^9, 3.514612443429145*^9}, {
>>   3.514613427110442*^9, 3.5146134734076815`*^9},
>>   3.514613562174443*^9, {3.5146136409098253`*^9,
>>   3.514613720004588*^9}}],
>>
>> Cell[CellGroupData[{
>>
>> Cell[BoxData[
>>  RowBox[{
>>  RowBox[{"(*", " ",
>>   RowBox[{
>>   "this", " ", "stands", " ", "exemplary", " ", "for", " ", "an",
>>    " ", "expression", " ", "expensive", " ", "to", " ", "evaluate"}],
>>    " ", "*)"}], "\n",
>>  RowBox[{"(*", " ",
>>   RowBox[{
>>   "after", " ", "once", " ", "evaluated", " ", "the", " ", "cell",
>>    " ", "will", " ", "be", " ", "marked", " ", "by", " ", "hand",
>>    " ", "as", " ", "non", " ", "evalauatable"}], " ", "*)"}], "\n",
>>  RowBox[{"(*", " ",
>>   RowBox[{
>>   "would", " ", "be", " ", "nice", " ", "if", " ", "the", " ", "non",
>>     " ", "evaluatable", " ", "marking", " ", "could", " ", "be", " ",
>>     "automated"}], " ", "*)"}], "\n",
>>  RowBox[{"Expand", "[",
>>   SuperscriptBox[
>>    RowBox[{"(",
>>     RowBox[{"x", "+", "y"}], ")"}], "2"], "]"}]}]], "Input",
>>  Evaluatable->False,
>>  CellChangeTimes->{{3.514611868752412*^9, 3.5146120165051975`*^9}, {
>>  3.514613501236163*^9, 3.5146135021893*^9}, {3.5146137213483553`*^9,
>>  3.514613723160878*^9}, {3.5146137558330317`*^9,
>>  3.5146137883642817`*^9}}],
>>
>> Cell[BoxData[
>>  RowBox[{
>>  SuperscriptBox["x", "2"], "+",
>>  RowBox[{"2", " ", "x", " ", "y"}], "+",
>>  SuperscriptBox["y", "2"]}]], "Output",
>>  CellChangeTimes->{3.514611341923472*^9}]
>> }, Open  ]],
>>
>> Cell[BoxData[
>>  RowBox[{
>>  RowBox[{"(*", " ",
>>   RowBox[{
>>   "her", " ", "we", " ", "get", " ", "the", " ", "expression", " ",
>>    "of", " ", "the", " ", "preceding", " ", "and", " ", "define",
>>    " ", "a", " ", "function", " ", "for", " ", "it"}], " ", "*)"}],
>>  "\n",
>>  RowBox[{
>>   RowBox[{
>>    RowBox[{"Ex", "[",
>>     RowBox[{"x_", ",", "y_"}], "]"}], "=",
>>    RowBox[{"NotebookGetExpression", "[", "]"}]}], ";"}]}]], "Input",
>>  CellChangeTimes->{{3.51461143789336*^9, 3.5146114714729896`*^9}, {
>>  3.51461151100601*^9, 3.514611576665202*^9}, {3.51461169146722*^9,
>>  3.5146117313278985`*^9}, {3.5146135213770456`*^9,
>>  3.5146135825028276`*^9}}],
>>
>> Cell[CellGroupData[{
>>
>> Cell[BoxData[
>>  RowBox[{
>>  RowBox[{"(*", " ",
>>   RowBox[{"test", " ", "the", " ", "defined", " ", "function"}], " ",
>>    "*)"}], "\n",
>>  RowBox[{"Ex", "[",
>>   RowBox[{"a", ",", "b"}], "]"}]}]], "Input",
>>  CellChangeTimes->{{3.5146114477219257`*^9, 3.5146114497063894`*^9}, {
>>  3.51461155541425*^9, 3.514611556461172*^9}, {3.514611709639909*^9,
>>  3.5146117106712055`*^9}, {3.514611837439311*^9,
>>  3.51461183870496*^9}, {3.5146138100517817`*^9,
>>  3.5146138104580317`*^9}}],
>>
>> Cell[BoxData[
>>  RowBox[{
>>  SuperscriptBox["a", "2"], "+",
>>  RowBox[{"2", " ", "a", " ", "b"}], "+",
>>  SuperscriptBox["b", "2"]}]], "Output",
>>  CellChangeTimes->{3.514614846234047*^9}]
>> }, Open  ]]
>> }
>>
>>
>
>
>