How to plot points with corresponding colour

Question

Hannah 2024-4-23

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https://ww2.mathworks.cn/matlabcentral/answers/2110566-how-to-plot-points-with-corresponding-colour

评论： Hannah 2024-4-26

Given I have an excel data where a1 is the first row of data, a2 is the second row of data and b is the corresponding label. B has either blue or red. When I plot it plots it all as a scatter plot but in blue. I want to make the points red when b says red for that label. How do i do this??

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Answer 1

Dyuman Joshi 2024-4-23

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https://ww2.mathworks.cn/matlabcentral/answers/2110566-how-to-plot-points-with-corresponding-colour#answer_1446306

在 MATLAB Online 中打开

(Assuming there are only red and blue colors for the plot) Use logical indexing -

%Check which elements of B are red
idx = strcmp(B, 'red');
f = figure;
hold on
%plot data with red color 
scatter(a1(idx), a2(idx), [], 'r')
%plot data with blue color
scatter(a2(~idx), a2(~idx), [], 'b')
hold off

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Hannah 2024-4-26

在 MATLAB Online 中打开

I tried that and it is not really working properly. I do not know if its my file that is the problem.

After uploading my excel dataset, this is how my codes look like

Dataset.Y(strcmp(Dataset.Y, 'red')) = {'-1'}
Dataset.Y(strcmp(Dataset.Y, 'blue')) = {'1'}
Dataset.Y = str2double(Dataset.Y)
data = table2array(Dataset)
%I think I am going wrong when plotting it or when turning the data into a
%matrix asthe number of rows do not match the height of the table