Re: Giving an arbitrary number of arguments to Manipulate using Apply
- To: mathgroup at smc.vnet.net
- Subject: [mg94651] Re: [mg94635] Giving an arbitrary number of arguments to Manipulate using Apply
- From: "Yoichi Aso" <aso at caltech.edu>
- Date: Fri, 19 Dec 2008 07:22:28 -0500 (EST)
- References: <20783330.1229605981096.JavaMail.root@m02>
Hi David,
Your method works great.
Thank you so much for the help !
Yoichi
2008/12/18 David Park <djmpark at comcast.net>:
> Sometimes I put Print statements into the code so I can see what the
> intermediate expressions are. The problem here is to prevent the Plot from
> being evaluate until after it is in the Manipulate statement. So use a dummy
> plot function and then substitute Plot after the Manipulate statement is
> composed. (Manipulate has the Attribute HoldAll.)
>
> testFunc[expr_, vars_] :=
> Module[{newFunc, args, i, p, plotf},
> newFunc = Apply[Plus, expr] /. vars[[1]] -> p;
> Print[newFunc];
> args :=
> Join[{plotf[newFunc, {p, 0, 10},
> Epilog -> Text[vars[[1]], Scaled[{.5, .9}]]]},
> Table[{vars[[i]], 0, 10}, {i, 1, Length[vars]}]];
> Print[args];
> Apply[Manipulate, args] /. plotf -> Plot]
>
> testFunc[{Sin[a x], b + x^2, -b x}, {x, a, b}]
>
>
> David Park
> djmpark at comcast.net
> http://home.comcast.net/~djmpark/
>
>
> From: Yoichi Aso [mailto:aso at caltech.edu]
>
> Hello,
>
> I have a problem with using Manipulate and Apply.
> I'd like to ask for your advice on this.
>
> Here is what I want to do:
> I have a list of expressions, expr, and a list of variables, vars.
> Each element of expr is a function of variables in vars.
> For example, expr={Sin[a x], x^2+b, - b x}; vars = {x,a,b}.
> Now, I want to write a function which takes expr and vars as arguments
> and does the following.
> First, it adds together the elements of expr to make a new function,
> newFunc.
> Then it creates a Manipulate object with sliders for all the variables in
> vars.
> The first argument of the Manipulate is a Plot of newFunc as a
> function of the first variable
> in vars.The value of the other variables are determined by the
> sliders. Along with the plot,
> the value of the first variable is shown as a Text object in the plot.
>
> Here is a code I came up with to implement the above task.
>
> testFunc[expr_, vars_] := Module[{newFunc, args, i, p},
> newFunc = Apply[Plus, expr] /. vars[[1]] -> p;
> args :=
> Join[{Plot[newFunc, {p, 0, 10}, Epilog -> Text[vars[[1]], {5, 1}]]},
> Table[{vars[[i]], 0, 10}, {i, 1, Length[vars]}]];
> Apply[Manipulate, args]
> ]
>
> However, when I execute, for example,
> testFunc[{Sin[a x], b + x^2, -b x}, {x, a, b}]
> it shows nothing in the plot area.
> I'm guessing it is because Join tries to evaluate the arguments, and
> at this moment, Plot cannot draw a graph
> because the variables a and b do not have numerical values.
> I enclosed the Join with Hold and used ReleaseHold around the Apply,
> but still no plot shown.
> I used Apply because I don't know the length of vars in advance.
>
> I'd appreciate it if anyone can suggest a solution to this problem.
>
> Thank you in advance,
> Yoichi
>
> --
> ----------------------------------------
> Yoichi Aso
> LIGO Laboratory, California Institute of Technology
> aso at caltech.edu or asoy01 at gmail.com
>
>
>
--
----------------------------------------
Yoichi Aso
LIGO Laboratory, California Institute of Technology
aso at caltech.edu or asoy01 at gmail.com