Matlab怎么繪制散點密度圖

小編給大家分享一下Matlab怎么繪制散點密度圖，相信大部分人都還不怎么了解，因此分享這篇文章給大家參考一下，希望大家閱讀完這篇文章后大有收獲，下面讓我們一起去了解一下吧！

效果

原理也很簡單，通過matlab自帶的ksdensity獲得網格每一點密度，通過密度擬合曲面，再計算每個數據點對應的概率，并將概率映射到顏色即可
為了怕大家找不到函數這次工具函數放到最前面

1工具函數完整代碼

function [CData,h,XMesh,YMesh,ZMesh,colorList]=density2C(X,Y,XList,YList,colorList)
[XMesh,YMesh]=meshgrid(XList,YList);
XYi=[XMesh(:) YMesh(:)];
F=ksdensity([X,Y],XYi);
ZMesh=zeros(size(XMesh));
ZMesh(1:length(F))=F;

h=interp2(XMesh,YMesh,ZMesh,X,Y);
if nargin<5
colorList=[0.2700         0    0.3300
    0.2700    0.2300    0.5100
    0.1900    0.4100    0.5600
    0.1200    0.5600    0.5500
    0.2100    0.7200    0.4700
    0.5600    0.8400    0.2700
    0.9900    0.9100    0.1300];
end
colorFunc=colorFuncFactory(colorList);
CData=colorFunc((h-min(h))./(max(h)-min(h)));
colorList=colorFunc(linspace(0,1,100)');

function colorFunc=colorFuncFactory(colorList)
x=(0:size(colorList,1)-1)./(size(colorList,1)-1);
y1=colorList(:,1);y2=colorList(:,2);y3=colorList(:,3);
colorFunc=@(X)[interp1(x,y1,X,'pchip'),interp1(x,y2,X,'pchip'),interp1(x,y3,X,'pchip')];
end
end

2參數說明

輸入：

• X,Y 散點坐標

• XList,YList 用來構造密度曲面網格的序列，其實就是把XLim，YLim分成小份，例如XList=0:0.1:10

• colorList 顏色表mx3數組，用來構造將高度映射到顏色函數的數據表

輸出：

• CData各個點對應顏色

• h 各個點對應核密度

• XMesh,YMesh,ZMesh 核密度曲面數據

• colorList 插值后更細密的顏色表

3使用方式

假如編寫了如下程序：

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];
scatter(PntSet(:,1),PntSet(:,2),'filled');

結果：

3.1散點賦色

將上面那段代碼改寫

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];

CData=density2C(PntSet(:,1),PntSet(:,2),-2:0.1:15,-2:0.1:15);
scatter(PntSet(:,1),PntSet(:,2),'filled','CData',CData);

3.2等高線圖

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];


[~,~,XMesh,YMesh,ZMesh,colorList]=density2C(PntSet(:,1),PntSet(:,2),-2:0.1:12,-2:0.1:12);
colormap(colorList)
contourf(XMesh,YMesh,ZMesh,10)

3.3帶直方圖的散點圖

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];

colorList=[0.9400    0.9700    0.9600
    0.8900    0.9300    0.9200
    0.8200    0.9100    0.8800
    0.6900    0.8500    0.7700
    0.5900    0.7800    0.6900
    0.5500    0.7500    0.6500
    0.4500    0.6500    0.5600
    0.4000    0.5800    0.4900
    0.3500    0.5100    0.4200
    0.2500    0.3600    0.3100
    0.1300    0.1700    0.1400];
CData=density2C(PntSet(:,1),PntSet(:,2),-2:0.1:15,-2:0.1:15,colorList);

set(gcf,'Color',[1 1 1]);

% 主分布圖
ax1=axes('Parent',gcf);hold(ax1,'on')
scatter(ax1,PntSet(:,1),PntSet(:,2),'filled','CData',CData);
ax1.Position=[0.1,0.1,0.6,0.6];

% X軸直方圖
ax2=axes('Parent',gcf);hold(ax2,'on')
histogram(ax2,PntSet(:,1),'FaceColor',[0.78 0.88 0.82],...
    'EdgeColor','none','FaceAlpha',0.7)
ax2.Position=[0.1,0.75,0.6,0.15];
ax2.YColor='none';
ax2.XTickLabel='';
ax2.TickDir='out';
ax2.XLim=ax1.XLim;

% Y軸直方圖
ax3=axes('Parent',gcf);hold(ax3,'on')
histogram(ax3,PntSet(:,2),'FaceColor',[0.78 0.88 0.82],...
    'EdgeColor','none','FaceAlpha',0.7,'Orientation','horizontal')
ax3.Position=[0.75,0.1,0.15,0.6];
ax3.XColor='none';
ax3.YTickLabel='';
ax3.TickDir='out';
ax3.YLim=ax1.YLim;

3.4帶直方圖的等高線圖

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];
colorList=[0.9300    0.9500    0.9700
    0.7900    0.8400    0.9100
    0.6500    0.7300    0.8500
    0.5100    0.6200    0.7900
    0.3700    0.5100    0.7300
    0.2700    0.4100    0.6300
    0.2100    0.3200    0.4900
    0.1500    0.2200    0.3500
    0.0900    0.1300    0.2100
    0.0300    0.0400    0.0700];
[~,~,XMesh,YMesh,ZMesh,colorList]=density2C(PntSet(:,1),PntSet(:,2),-2:0.1:13,-2:0.1:13,colorList);


set(gcf,'Color',[1 1 1]);
% 主分布圖
ax1=axes('Parent',gcf);hold(ax1,'on')
colormap(colorList)
contourf(XMesh,YMesh,ZMesh,10,'EdgeColor','none')
ax1.Position=[0.1,0.1,0.6,0.6];
ax1.TickDir='out';

% X軸直方圖
ax2=axes('Parent',gcf);hold(ax2,'on')
[f,xi]=ksdensity(PntSet(:,1));
fill([xi,xi(1)],[f,0],[0.34 0.47 0.71],'FaceAlpha',...
    0.3,'EdgeColor',[0.34 0.47 0.71],'LineWidth',1.2)
ax2.Position=[0.1,0.75,0.6,0.15];
ax2.YColor='none';
ax2.XTickLabel='';
ax2.TickDir='out';
ax2.XLim=ax1.XLim;

% Y軸直方圖
ax3=axes('Parent',gcf);hold(ax3,'on')
[f,yi]=ksdensity(PntSet(:,2));
fill([f,0],[yi,yi(1)],[0.34 0.47 0.71],'FaceAlpha',...
    0.3,'EdgeColor',[0.34 0.47 0.71],'LineWidth',1.2)
ax3.Position=[0.75,0.1,0.15,0.6];
ax3.XColor='none';
ax3.YTickLabel='';
ax3.TickDir='out';
ax3.YLim=ax1.YLim;

4使用方式擴展–與ggplot修飾器聯動

ggplot風格修飾器：(點擊圖片跳轉鏈接)

示例1

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];

ax=gca;
ax.XLim=[-1 13];
ax.YLim=[-1 13];
ax=ggplotAxes2D(ax);

CData=density2C(PntSet(:,1),PntSet(:,2),0:0.1:15,0:0.1:15);
scatter(PntSet(:,1),PntSet(:,2),'filled','CData',CData);

是不是瞬間有那味了：

示例2

PntSet1=mvnrnd([2 3],[1 0;0 2],800);
PntSet2=mvnrnd([6 7],[1 0;0 2],800);
PntSet3=mvnrnd([8 9],[1 0;0 1],800);

PntSet=[PntSet1;PntSet2;PntSet3];

ax=gca;
ax.XLim=[-3 13];
ax.YLim=[-3 13];
ax=ggplotAxes2D(ax);

[~,~,XMesh,YMesh,ZMesh,colorList]=density2C(PntSet(:,1),PntSet(:,2),-2:0.1:12,-2:0.1:12);
colormap(colorList)
contourf(XMesh,YMesh,ZMesh,10)

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