Avoid problem with dynamic ListStepPlot?

Questions
,
1

Dear Community,

I’m trying to construct a dynamic ListStepPlot via locators. The three locators (pt1, pt2, pt3) are confined inside a polygon. Upon running the code however the ListStepPlot constructed from the dynamic points does not show up. Could someone pls. have a look and help? The notebook is attached.

Tx in advance,

best regards
Andras

2

You cannot put a ListStepPlot that way inside Graphics. You can combine Graphics with ListStepPlot with Show or Inset.

3

Dear Gianluca,

Tx for the tip. Show works and the ListStepPlot shows up correctly initially, but it is still not dynamic and it does not move as I drag the Locators. How could I make it dynamic? (Notebook attached)

Tx for the help in advance,
best regards
Andras

4

Dear Gianluca,

Could you pls. check my updated notebook BD_3P_ListStepPlot_Show.nb above? I could not manage to make LisStepPlot dynamic.

Tx in advance,
best regards

Andras

5

The ListStepPlot may overshadow the Locators that are in the same positions. Try writing ListStepPlot before the Graphics, so that the Locators come on top of the plot, with a Dynamic before Show.

6

Dear Gianluca,

Did not work either. No problem, I’ll try another solution, I gues I’ll write a function for that.

BTW may I have another question? How could I add a flying annotation to a Locator? I.e. a label (e.g. “P1”), which moves together with the Locator upon draging?

Tx in advance
best regards

Andras

7

Try

Graphics[Dynamic@ First@ ListStepPlot[{pt1, pt2, pt3}]]
8

This way it seems to work:

DynamicModule[{pt1 = {0.8, qgHSZ[0.2] }, pt2 = {0.6, qgHSZ[0.5] },
  pt3 = {0.3, qgHSZ[0.25] }, from = .2 , x},
 Dynamic@Show[
   ListStepPlot[ {pt1 , pt2 , pt3} , Axes -> False],
   Graphics[{Line[{{from , pt1[[2]]}, pt1}], 
     LightBlue , {Opacity[0.01], EdgeForm[Thin], poly},
     l1 = 
      Locator[Dynamic[
        pt1, (pt1 = RegionNearest[poly, #]; 
          from = If[pt1[[2]] > 4.55, 
            x /. NSolve[qgHSZ[x] == pt1[[2]], x][[1]], 0.]) & ]],
      l2 = Locator[Dynamic[pt2, (pt2 = RegionNearest[poly, #]) &]],
      l3 = Locator[Dynamic[pt3, (pt3 = RegionNearest[poly, #]) &]],
     Red, Text["P1", pt1, 2 {1, 1}]}],
   Axes -> True, AxesOrigin -> {0, 0}, AspectRatio -> 1 , 
   PlotRange -> CoordinateBounds[poly], 
   PlotRangePadding -> Scaled[.05], Ticks -> Automatic]]
9

@Michael

Thank you very much

best regards

Andras

10

Dear Gianluca,

Works perfect, thank you very much, great help to my work :slight_smile:

best regards

Andras