Extract data using histogram2()

Question

sagun subedi 2020-7-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/557791-extract-data-using-histogram2

回答： Image Analyst 2020-7-1

采纳的回答： sagun subedi

Is it possible to extract data (x-coordinates and y-coordinates) using the syntax histogram2()?

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sagun subedi 2020-7-1

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Answer 1

sagun subedi 2020-7-1

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https://ww2.mathworks.cn/matlabcentral/answers/557791-extract-data-using-histogram2#answer_459697

在 MATLAB Online 中打开

%%%%input
location = rand(10, 2); %%%representing x and y coordinates
[N, x,y,binx,biny] = histcounts2(location(:, 1), location(:, 2));
%%%%output
N = 2×2    
     3     5
     1     1
x = 1×3    
     0     5    10
y = 1×3    
     0     5    10
binx = 10×1    
     1
     1
     1
     1
     1
     1
     1
     2
     1
     2
biny = 10×1    
     2
     2
     1
     1
     1
     2
     2
     1
     2
     2

Number of count is first bin N(1) = 3 and so on. My question is how to get the actual coordinates as shown in the figure above for each bin with edges x and y.

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Steven Lord 2020-7-1

在 MATLAB Online 中打开

isInFirstBin = (binx == 1 & biny == 1);
pointsInFirstBin = location(isInFirstBin, :)
isInBin12 = (binx == 1 & biny == 2);
pointsInBin12 = location(isInBin12, :)

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Answer 2

Steven Lord 2020-7-1

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https://ww2.mathworks.cn/matlabcentral/answers/557791-extract-data-using-histogram2#answer_459565

If you want the data that was passed into histogram2 retrieve the Data property of the histogram.

If you want the edges of the bins, get the XBinEdges and YBinEdges properties.

For the bin counts (raw or with the specified Normalization applied) see the BinCounts and Values properties.

If none of those are what you mean by "data" please clarify what specifically you want to extract.

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sagun subedi 2020-7-1

I am really sorry, but this is not working either.

Steven Lord 2020-7-1

Please show a small sample of your data, show how you called histcounts2 on that data, and explain what "not working" means. Did it not give you the results you expected? Did it throw an error and if it did what was the full text of that error, all the text in red? With this information we may be able to help you do what you asked.

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Answer 3

Image Analyst 2020-7-1

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/557791-extract-data-using-histogram2#answer_459742

在 MATLAB Online 中打开

Try this:

clc;    % Clear the command window.
fprintf('Beginning to run %s.m.\n', mfilename);
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
numPoints = 20;
xy = rand(numPoints, 2); % Representing x and y coordinates
plot(xy(:, 1), xy(:, 2), 'b.', 'MarkerSize', 20);
grid on;
xEdges = [0, 0.5, 1];
yEdges = [0, 0.25, 0.5, 0.75, 1];
xticks(xEdges);
yticks(yEdges);
xlim([min(xEdges), max(xEdges)]);
ylim([min(yEdges), max(yEdges)]);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
counts = histcounts2(xy(:, 1), xy(:, 2), xEdges, yEdges)
% With counts, the x counts are rows and the y are columns.
% Place the count in each bin
for kx = 1 : size(counts, 1)
	xt = mean([xEdges(kx), xEdges(kx + 1)]);
	for ky = 1 : size(counts, 2)
		yt = mean([yEdges(ky ), yEdges(ky + 1)]);
		textLabel = sprintf('Count = %d', counts(kx, ky));
		text(xt, yt, textLabel, 'Color', 'r', 'FontSize', 12, 'HorizontalAlignment', 'center');
	end
end
fprintf('Done running %s.m.\n', mfilename);