showing different parts of a dataset with different symbols in a scatterplot

Hello there

I have a small and confusing question, would you please tell me how to show my data with different symbols within a scatter plot?? lets say I wanna create a scatter plot which has 60 inputs, I would like to show the first 20 with for instance triangle, the next 10 with circles and the rest with asterisks. I think it could be easy but I got totally confused about it. thank you all in advance

Answer 1

[Sean de Wolski]

% Synthetic data
x = rand(60,1);
y = rand(60,1);

% Plotting
scatter(x(1:20),y(1:20),'r*');
hold on
scatter(x(21:30),y(21:30),'b^');
scatter(x(31:end),y(31:end),'g<');

Answer 2

[Nima]

thx a lot Sean

Answer 3

[Nima]

Dear Sean but when i want to add the refline line it gives me three reflines I just wanna have one for the whole scatter plot

[Sean de Wolski]

Then calculate the refline coefficients with polyfit with the whole dataset:

% Synthetic data
x = cumsum(rand(60,1));
y = cumsum(rand(60,1));

% Plotting
scatter(x(1:20),y(1:20),'r*');
hold on
scatter(x(21:30),y(21:30),'b^');
scatter(x(31:end),y(31:end),'g<');

mb = polyfit(x,y,1);
refline(mb)