matlab:散点图具有大量数据点 [英] matlab: scatter plots with high number of datapoints

问题描述

我正在尝试绘制散点图，例如:

scatter(coor(:, 2), coor(:, 3), 1, coor(:, 4));

问题是，我要绘制的坐标数量很多(〜100 000).绘制它需要花费很长时间，并且当我尝试将图形导出到tiff时-matlab死了好几分钟了...任何改善绘制的解决方案，或者至少是tiff导出?

忘了提及，第三坐标(coor(:, 4))是一个颜色代码.

所以，当我使用散点图(如上)时，我在下图中有类似的东西，这就是我想要的样子(只是它的超慢速度，我无法导出它):

当我这样做时:

plot3(coor(:, 2)，coor(:, 3)，coor(:, 4)，'.')

效果不再那么酷(注意:图像不是来自相同的坐标...):

解决方案

您可以使用 plot ，但是所有点都具有相同的颜色.但是，您可以将集合划分为不同的子集，并以各自的颜色对其进行绘制:

N = 100000;
x = rand(N,1);
y = rand(N,1);
C = sin(2*x)+y;

cdivs = 10;
[~, edges] = hist(C,cdivs-1);
edges = [-Inf edges Inf]; % to include all points
[Nk, bink] = histc(C,edges);

figure;
hold on;
cmap = jet(cdivs);
for ii=1:cdivs
    idx = bink==ii;
    plot(x(idx),y(idx),'.','MarkerSize',4,'Color',cmap(ii,:));
end

colormap(cmap)
caxis([min(C) max(C)])
colorbar

响应速度已经比scatter(x,y,1,C)好，后者给出相同的绘图，但是具有更高的色彩分辨率(可以在我上面的代码中进行调整).

I'm trying to plot scatter, something like:

scatter(coor(:, 2), coor(:, 3), 1, coor(:, 4));

The problem is, that I have quite big number of coordinates to plot (~100 000). Its taking long time to plot it, and when I try to export figure to tiff - then matlab is dead for goooood few minutes... Any solution to improve plotting, or at least tiff export?

EDIT: Forgot to mention, 3rd coordinate (coor(:, 4)) is a color code.

So, when I'm using scatter (as above), I have something like on the image below, and thats exactly how I want to see it (just its super slow and I can't export that):

When I do:

plot3(coor(:, 2), coor(:, 3), coor(:, 4), '.')

effect is not as cool any more (note: images are not from the same coordinates...) :

解决方案

You can use plot, but then all points have the same color. However, you can divide the set in different subsets and plot them each with their own color:

N = 100000;
x = rand(N,1);
y = rand(N,1);
C = sin(2*x)+y;

cdivs = 10;
[~, edges] = hist(C,cdivs-1);
edges = [-Inf edges Inf]; % to include all points
[Nk, bink] = histc(C,edges);

figure;
hold on;
cmap = jet(cdivs);
for ii=1:cdivs
    idx = bink==ii;
    plot(x(idx),y(idx),'.','MarkerSize',4,'Color',cmap(ii,:));
end

colormap(cmap)
caxis([min(C) max(C)])
colorbar

which responds already a lot better than scatter(x,y,1,C) which gives about the same plot, but with higher color resolution (which is adjustable in my code above).

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