how to plot data points with different color in scatter plot?

Question

Lei 2012-5-24

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/39322-how-to-plot-data-points-with-different-color-in-scatter-plot

hello,everyone. I have a very large matrix, thousands of rows and 15 columns. Now i wanna analyze four variables(columns). I used the scatter plot for plotting each of the two variables. My question is how can I plot different colors for different groups of data in scatter plot. I wrote a if statement but its very slow, so I am wondering anyone have any better ways to do it.

 for i=1: length(PaskapooFm4(:,14));
if PaskapooFm4(i,14)==1
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.b');hold on;
   elseif PaskapooFm4(i,14)==2
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.g');hold on;
   elseif PaskapooFm4(i,14)==3
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.r');hold on;
   elseif PaskapooFm4(i,14)==4
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.c');hold on;
   elseif PaskapooFm4(i,14)==5
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.m');hold on;
   elseif PaskapooFm4(i,14)==6
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.y');hold on;
   elseif PaskapooFm4(i,14)==7
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'.b');hold on;
   elseif PaskapooFm4(i,14)==8
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'h');hold on;
   elseif PaskapooFm4(i,14)==9
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'>');hold on;
   elseif PaskapooFm4(i,14)==10
   scatter(PaskapooFm4(i,3),PaskapooFm4(i,12),'<');hold on;
end
xlabel('GAMMA(API)');ylabel('RES(DG)(OHM-M)');
title('Crossplot of Gamma and RESD')
end

the above code used to plot two variables (column 3 and column 12), and each row is in 10 categories as indicated by column 14. Column 14 are just numbers: 1 to 10. So what i did here is using scatter plot for plotting the two varibales and assign different color for each number( 1 to 10). However, this is very slow and the code is long. Anybody could think of a better way? Many thanks! BTW, I also need to figure out those 4 variables' relationship. How can I fit a best line to the scatter plot? because there are so man different ones(liner,quadratic,third order...). I mean how can I decide which one is the best fit. Or any other better ways to visualize multidimensional data? I tried to use plotmatrix,pca. etc....

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Oleg Komarov 2012-5-24

Have you checked gscatter?

Lei 2012-5-24

Hi oleg,I did!

But i am not sure about the meaning of group in gscatter cauz I have created my own group,which is column 14 (number 1 to number 10),i.e., 10 different groups. I thought my group is different from the group in gscatter, am I right? I am not sure about this

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