Skip to main content

How to use custom Dynamic inside Manipulate


I was wondering if it is possible to use a custom Dynamic[var, function] inside a Manipulate. The reason for the need is this:


Suppose you have a time consuming computation like


timeConsuming[x_] := (Pause[1]; x)

and you want to use it in a Manipulate. Writing


DynamicModule[{y},
Manipulate[

y = timeConsuming[x]; {x, y, other},
{x, 0, 1},
{other, 0, 1}]
]

entails the following issue: you have to wait for timeConsuming to be computed even when you change other and leave x unmodified. A (simple) solution is to code the dynamic by hand:


DynamicModule[{x = 0, y = timeConsuming[0], other = 0},
Panel@Column[{
Grid[{
{"x", Slider[Dynamic[x, (x = #; y = timeConsuming[x]) &], {0, 1}]},

{"other", Slider[Dynamic[other], {0, 1}]}
}],
Dynamic@{x, y, other}
}]
]

This is feasible, but as a drawback makes you renounce all other Module's conveniences.


I tried coding something like


Module[(* result *), {x, 0, 1, some-suitable-function}]


but had no success in the attempt. A (clean) use of Manipulate would be much appreciated.


Just to summarize, the question is: How can I make some statements be executed only when some specified controls are touched?



Answer



Is this what you're after?


timeConsuming[x_] := (Pause[1]; x);
DynamicModule[{y},
Manipulate[y = timeConsuming[x]; {Dynamic@x, y, Dynamic@other},
{x, 0, 1}, {other, 0, 1},
SynchronousUpdating -> False]
]


SynchronousUpdating -> False keeps the front end from being blocked while timeConsuming is computing, and Dynamic lets different segments be updated. So x and other both update when the sliders are moved, and y is updated one second after x is.


Comments

Popular posts from this blog

front end - keyboard shortcut to invoke Insert new matrix

I frequently need to type in some matrices, and the menu command Insert > Table/Matrix > New... allows matrices with lines drawn between columns and rows, which is very helpful. I would like to make a keyboard shortcut for it, but cannot find the relevant frontend token command (4209405) for it. Since the FullForm[] and InputForm[] of matrices with lines drawn between rows and columns is the same as those without lines, it's hard to do this via 3rd party system-wide text expanders (e.g. autohotkey or atext on mac). How does one assign a keyboard shortcut for the menu item Insert > Table/Matrix > New... , preferably using only mathematica? Thanks! Answer In the MenuSetup.tr (for linux located in the $InstallationDirectory/SystemFiles/FrontEnd/TextResources/X/ directory), I changed the line MenuItem["&New...", "CreateGridBoxDialog"] to read MenuItem["&New...", "CreateGridBoxDialog", MenuKey["m", Modifiers-...

How to thread a list

I have data in format data = {{a1, a2}, {b1, b2}, {c1, c2}, {d1, d2}} Tableform: I want to thread it to : tdata = {{{a1, b1}, {a2, b2}}, {{a1, c1}, {a2, c2}}, {{a1, d1}, {a2, d2}}} Tableform: And I would like to do better then pseudofunction[n_] := Transpose[{data2[[1]], data2[[n]]}]; SetAttributes[pseudofunction, Listable]; Range[2, 4] // pseudofunction Here is my benchmark data, where data3 is normal sample of real data. data3 = Drop[ExcelWorkBook[[Column1 ;; Column4]], None, 1]; data2 = {a #, b #, c #, d #} & /@ Range[1, 10^5]; data = RandomReal[{0, 1}, {10^6, 4}]; Here is my benchmark code kptnw[list_] := Transpose[{Table[First@#, {Length@# - 1}], Rest@#}, {3, 1, 2}] &@list kptnw2[list_] := Transpose[{ConstantArray[First@#, Length@# - 1], Rest@#}, {3, 1, 2}] &@list OleksandrR[list_] := Flatten[Outer[List, List@First[list], Rest[list], 1], {{2}, {1, 4}}] paradox2[list_] := Partition[Riffle[list[[1]], #], 2] & /@ Drop[list, 1] RM[list_] := FoldList[Transpose[{First@li...

mathematical optimization - Minimizing using indices, error: Part::pkspec1: The expression cannot be used as a part specification

I want to use Minimize where the variables to minimize are indices pointing into an array. Here a MWE that hopefully shows what my problem is. vars = u@# & /@ Range[3]; cons = Flatten@ { Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; Minimize[{Total@((vec1[[#]] - vec2[[u[#]]])^2 & /@ Range[1, 3]), cons}, vars, Integers] The error I get: Part::pkspec1: The expression u[1] cannot be used as a part specification. >> Answer Ok, it seems that one can get around Mathematica trying to evaluate vec2[[u[1]]] too early by using the function Indexed[vec2,u[1]] . The working MWE would then look like the following: vars = u@# & /@ Range[3]; cons = Flatten@{ Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; NMinimize[ {Total@((vec1[[#]] - Indexed[vec2, u[#]])^2 & /@ R...