How can I create a table of sliders?

Question

I'm trying to do the following:

I have a table:

w = Table[ToExpression[ToString[h] <> ToString[i]], {i, 1, Length[c]}]

This table is suposed to generate variables, like the following list:

{h1, h2, h3, h4, h5, h6, h7, h8, h9, h10, h11}

I'm trying to create a table of vertical sliders with this by adding this to the code:

w = Table[VerticalSlider[Dynamic[ToExpression[ToString[h] <> ToString[i]]]], {i, 1, Length[c]}]

It create a it gives me an error:

Set::write: "Tag ToExpression in \!\(ToExpression[\"hi\"]\) is Protected.

I'm aware that this may not be the best way todo this but it's all I can imagine, I guess the other feasible way would be with loops, I don't know. Can you help me?

Answer 1

The problem is that Dynamic is preventing ToExpression from evaluating to a symbol. When you drag the slider it's trying to evaluate:

ToExpression[ToString[h] <> ToString[1] = 0.1

and you get a message about not being able to set the value of ToExpression.

I would use With to create the symbols and insert them into the Dynamic:

w = Table[With[{var = ToExpression[ToString[h] <> ToString[i]]}, 
       VerticalSlider[Dynamic[var]]], {i, 1, Length[c]}]

Answer 2

Depending on what you're going to do next, this might be useful:

 x = {.1, .2, .3, .4, .5};
 Outer[Slider[Dynamic[x[[#1]]], {0, 1}] &, Range[Length[x]]]

This creates a collection of sliders, one for each element of x. The values of x provide the initialization, and when you move a slider, the corresponding element of x changes. You can see this happening in real time using

 Dynamic[x]