Arctan Binning, from Plot to Histogram, the tricks
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21-01-2021 - |
Question
Based on Sjoerd, great solution and extension on From Cartesian Plot to Polar Histogram using Mathematica, please consider the Following :
list = {{21, 16}, {16, 14}, {11, 11}, {11, 12},
{13, 15}, {18, 17}, {19, 11}, {17, 16}, {16, 19}}
ScreenCenter = {20, 15}
ListPolarPlot[{ArcTan[##], EuclideanDistance[##]} & @@@ (# - ScreenCenter & /@ list),
PolarAxes -> True, PolarGridLines -> Automatic, Joined -> False,
PolarTicks -> {"Degrees", Automatic},
BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold,
FontSize -> 12}, PlotStyle -> {Red, PointSize -> 0.02}]
Module[{Countz, maxScale, angleDivisions, dAng},
Countz = Reverse[BinCounts[Flatten@Map[ArcTan[#[[1]] - ScreenCenter[[1]], #[[2]] -
ScreenCenter[[2]]] &, list, {1}], {-\[Pi], \[Pi], \[Pi]/6}]];
maxScale = 4;
angleDivisions = 12;
dAng = (2 \[Pi])/angleDivisions;
SectorChart[{ConstantArray[1, Length[Countz]], Countz}\[Transpose],
SectorOrigin -> {-\[Pi]/angleDivisions, "Counterclockwise"},
PolarAxes -> True,
PolarGridLines -> Automatic,
PolarTicks -> {Table[{i \[Degree] + \[Pi]/angleDivisions,i \[Degree]},
{i, 0, 345, 30}], Automatic},
ChartStyle -> {Directive[EdgeForm[{Black, Thickness[0.005]}], Red]},
BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold,
FontSize -> 12}, ImageSize -> 400]]
As you can see the histogram shows a rotational symmetry of what it should. I tried everything to get those straight but did not succeed. Without Reverse it is worst. I tried RotateRight without success.I feel the problem is in my BinCount. ArcTan output from -Pi to Pi whereas Sjoerd suggested I needed to go from 0 to 2Pi. But I don`t understand how to do so.
EDIT : Problem solved. Thanks to Sjoerd, Belisarius, Heike solutions, I am able to show a histogram of the eye fixations locations given the center of gravity of an image.
Solution
You could use the ChartElementFunction
option to position the sectors accurately. The first argument of ChartElementFunction
is of the form {{angleMin, angleMax}, {rMin,rMax}}
. The first sector has bounds {angleMin, angleMax} = {-Pi/12, Pi/12}
, the second one {Pi/12, 3 Pi/12}
, etc. Therefore, to get the right rotation you could do something like
Module[{Countz, maxScale, angleDivisions, dAng},
maxScale = 4;
angleDivisions = 12;
dAng = (2 \[Pi])/angleDivisions;
Countz = BinCounts[
Flatten@Map[ArcTan @@ (# - ScreenCenter) &, list, {1}],
{-Pi, Pi, dAng}];
SectorChart[{ConstantArray[1, Length[Countz]], Countz}\[Transpose],
SectorOrigin -> {-\[Pi]/angleDivisions, "Counterclockwise"},
PolarAxes -> True, PolarGridLines -> Automatic,
PolarTicks -> {Table[{i \[Degree] + \[Pi]/angleDivisions,
i \[Degree]}, {i, 0, 345, 30}], Automatic},
ChartStyle -> {Directive[EdgeForm[{Black, Thickness[0.005]}], Red]},
BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold, FontSize -> 12},
ImageSize -> 400,
ChartElementFunction ->
Function[{range}, Disk[{0, 0}, range[[2, 2]], - 11 Pi/12 + range[[1]]]]]]
OTHER TIPS
Just checking right now, but your first plot seems flawed:
list = {{21, 16}, {16, 14}, {11, 11}, {11, 12}, {13, 15},
{18, 17}, {19, 11}, {17, 16}, {16, 19}};
ScreenCenter = {20, 15};
Show[ListPlot[list, PlotStyle -> Directive[PointSize[Medium], Purple]],
Graphics[
{Red, PointSize[Large], Point[ScreenCenter],
Circle[ScreenCenter, 10]}],
AspectRatio -> 1, Axes -> False]
ListPolarPlot[{ArcTan[Sequence @@ ##], Norm[##]} &/@ (#-ScreenCenter & /@ list),
PolarAxes -> True,
PolarGridLines -> Automatic,
Joined -> False,
PolarTicks -> {"Degrees", Automatic},
BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold, FontSize -> 12},
PlotStyle -> {Red, PointSize -> 0.02}]
Edit
I did not followed all your code, but a reflection on the Screen Center seems to fix the thing:
Module[{Countz, maxScale, angleDivisions, dAng},
Countz = BinCounts[
{ArcTan[Sequence @@ ##]} & /@ (# + ScreenCenter & /@ -list),
{-Pi, Pi, Pi/6}];
maxScale = 4;
angleDivisions = 12;
dAng = (2 Pi)/angleDivisions;
SectorChart[{ConstantArray[1, Length[Countz]], Countz}\[Transpose],
SectorOrigin -> {-Pi/angleDivisions, "Counterclockwise"},
PolarAxes -> True,
PolarGridLines -> Automatic,
PolarTicks -> {Table[{i \[Degree] + Pi/angleDivisions,
i \[Degree]}, {i, 0, 345, 30}], Automatic},
ChartStyle -> {Directive[EdgeForm[{Black, Thickness[0.005]}], Red]},
BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold,
FontSize -> 12},
ImageSize -> 400]]
Edit
Here you may see the small misalignment in my code, that is solved in Heike's answer (vote for it!)
Show[Module[{Countz, maxScale, angleDivisions, dAng},
Countz = BinCounts[{ArcTan[
Sequence @@ ##]} & /@ (# +
ScreenCenter & /@ -list), {-\[Pi], \[Pi], \[Pi]/6}];
maxScale = 4;
angleDivisions = 12;
dAng = (2 \[Pi])/angleDivisions;
SectorChart[{ConstantArray[1, Length[Countz]], Countz}\[Transpose],
SectorOrigin -> {-\[Pi]/angleDivisions, "Counterclockwise"},
PolarAxes -> True, PolarGridLines -> Automatic,
PolarTicks -> {Table[{i \[Degree] + \[Pi]/angleDivisions,
i \[Degree]}, {i, 0, 345, 30}], Automatic},
ChartStyle -> {Directive[EdgeForm[{Black, Thickness[0.005]}],
Red]}, BaseStyle -> {FontFamily -> "Arial", FontWeight -> Bold,
FontSize -> 12}, ImageSize -> 400]],
ListPlot[Plus[# - ScreenCenter] & /@ list/2.5,
PlotMarkers -> Image[CrossMatrix[10], ImageSize -> 10]]
]