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I am trying to get the red dot track vertically the green point on the graph, but they are different plots. And because of this I am experiencing difficulty.

There is a technique best to do this?

There is something about Piecewise, but didn't know how to apply.

velcarro = 69.2
dist1 = 8.4
time1 = 8.4/69.2
dist2 = 1.9
time2 = 27/60 // N
carro = {time1, dist1}
andando = {time2, dist2}
final = {time1 + time2, dist1 + dist2}

f[xP2_] := Evaluate[Fit[{{0, 0}, final}, {1, xP2}, xP2]];
xP2 = Subdivide[0, final[[1]], 30];
yP2 = f[#] & /@ xP2;
coordP2 = Transpose[{xP2, yP2}];

Table[
 Show[{
     Plot[
      Evaluate[Fit[{{0, 0}, carro}, {1, x}, x]], 
      {x, 0, time1}, 
      PlotStyle -> {Directive[Red, Thickness[0.005]]}
     ], 
     Plot[
      Evaluate[Fit[{carro, final}, {1, x}, x]], 
      {x, time1, final[[2]]}, 
      PlotRange -> {{final[[1]], 0}, {0, final[[2]]}}, 
      PlotStyle -> {Directive[Red, Thickness[0.005]]}
     ], 
     Plot[
      Evaluate[Fit[{{0, 0}, final}, {1, x}, x]], 
      {x, 0, final[[1]]}, 
      PlotStyle -> {Directive[Dashed, Green, Thickness[0.005]]}
     ], 
     p1 = Graphics[{Red, PointSize[0.03], Point[{0, 0}]}], 
     p2 = Graphics[{Green, PointSize[0.03], Point[#]}]
    }, 
    PlotRange -> {{0, final[[1]]}, {0, final[[2]]}}], 1
   ] & /@ coordP2

enter image description here

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2
  • $\begingroup$ And how to eliminate { and } of my animation? $\endgroup$
    – LCarvalho
    Commented Oct 3, 2016 at 15:58
  • $\begingroup$ The coordinates of your red Point don't change with the function argument $\endgroup$
    – Jason B.
    Commented Oct 3, 2016 at 18:16

1 Answer 1

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Clear["Global`*"]
velcarro = 69.2;
dist1 = 8.4;
time1 = 8.4/69.2;
dist2 = 1.9;
time2 = 27/60 // N;
carro = {time1, dist1};
andando = {time2, dist2};
final = {time1 + time2, dist1 + dist2};

g1 = Plot[Evaluate[Fit[{{0, 0}, carro}, {1, x}, x]], {x, 0, time1}, 
   PlotStyle -> {Directive[Red, Thickness[0.005]]}];

g2 = Plot[Evaluate[Fit[{carro, final}, {1, x}, x]], {x, time1, final[[2]]}, 
   PlotRange -> {{final[[1]], 0}, {0, final[[2]]}}, 
   PlotStyle -> {Directive[Red, Thickness[0.005]]}];

g3 = Plot[Evaluate[Fit[{{0, 0}, final}, {1, x}, x]], {x, 0, final[[1]]}, 
   PlotStyle -> {Directive[Dashed, Green, Thickness[0.005]]}];

t = Subdivide[0, final[[1]], 30];

xPointG[x_] := Evaluate[Fit[{{0, 0}, final}, {1, x}, x]];

yPointG = xPointG[#] & /@ t;

coordPointG = Transpose[{t, yPointG}];

xPointV1[x_] := Evaluate[Fit[{{0, 0}, carro}, {1, x}, x]];

yPointV1 = xPointV1[#] & /@ Take[t, 7];

coordPointV1 = Transpose[{Take[t, 7], yPointV1}];

xPointV2[x_] := Evaluate[Fit[{carro, final}, {1, x}, x]];

yPointV2 = xPointV2[#] & /@ Take[t, {8, -1}];

coordPointV2 = Transpose[{Take[t, {8, -1}], yPointV2}];

coordPointV = Join[coordPointV1, coordPointV2];

pV = Graphics[{Red, PointSize[0.03], Point[#]}] & /@ coordPointV;

pG = Graphics[{Green, PointSize[0.03], Point[#]}] & /@ coordPointG;

frames = Flatten @@Table[
     Show[{g1, g2, g3, pV[[#]], pG[[#]]}, 
      PlotRange -> {{0, final[[1]]}, {0, final[[2]]}}], 1] & /@ 
   Range[Length[t]];

Export["C:\\Users\\LMC\\moviment.gif", frames];

enter image description here

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