Same color lines in legend using a for loop

Question

Noah 2022-9-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1808885-same-color-lines-in-legend-using-a-for-loop

评论： Mathieu NOE 2023-2-12

When I try and run this code, all the lines in the legend show up as red lines instead of different colors.

hold on 
for i = 1:length(g)
if g(i) >= 2 
  
plot(x,y,Color='b'); 
else 
plot(x2,y2,Color='r'); 
  
  
end
end
 hold off
 
 hold on 
plot(x2,y2,Color='y');
plot(x3,x3,,Color='m');
hold off
 
 legend('l1','l2','l3','l4')

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Dyuman Joshi 2022-9-20

1 - Do not use equal-to "=" sign between 'Color', and color value, inside the plot() function.

Use a comma ","

2 - Using "hold on" immediately after "hold off" seems a bit redundant.

3 - You might be overwriting the x2-y2 curve, color 'r' with itself x2-y2 curve, color 'y'. In the case, you would only find 3 curves

Other than this, I can not say what the error is (if it occurs after considering above points), data for the variables will be required to make any more comments on it.

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Answer 1

Mathieu NOE 2022-9-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1808885-same-color-lines-in-legend-using-a-for-loop#answer_1057865

在 MATLAB Online 中打开

hello

why make simple things complicated ?

if you have only 4 arrays to plot , you could do directly the plot like this - and the colors appears correctly in the legend box

% dummy data
x = 1:5;
y = 2*x+1;
x2 = 1.5*x;
y2 = 2*y+1;
x3 = 0.5*x;
% plot
figure
plot(x,y,'b',x2,y2,'r',x2+1,y2+1,'y',x3,x3,'m');
 legend('l1','l2','l3','l4')

if you want a for loop and assign a color / line style different to each line , you can do this :

 t = 0:pi/50:2*pi;
MarkerStyle={'o','+','*','x','s','d','v','>'};
Colors=[1 0 0; 1 0 1; 0 1 0; 0.4660 0.6740 0.1880; 0 0 1; 0.3010 0.7450 0.9330; 0.8500 0.3250 0.0980; 0.9290 0.6940 0.1250]
figure(1),hold on 
for ck = 1:8
    p = plot(t,sin((1+0.2*ck)*t),'LineWidth',2,'Color',Colors(ck,:),'Marker',MarkerStyle{ck});
    leg_str{ck} = (['Line #' num2str(ck)]);
end
legend(leg_str);

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Sophia Ehlers 2023-2-11

在 MATLAB Online 中打开

This does'nt work for me, is it possible that this only works for plots but not for error bars? Or what other possible mistakes have i made?

color = [0.933 0.443 0.0; 0.0 0.30588 0.62351; 0.0 0.6588 0.475; 161./255 217./255 248./255; 0./255 120./255 120./255];
Legends={'10,2 °C'; '15 °C'; '21,8 °C'; '26 °C'; '30 °C'};
%get multiple sets of data
for file_j = 1:5
    file = strcat('Kennlinien', '_', num2str(file_j), '.txt');
data = load(file,'txt');
U = data(:,1); % Voltage Data
I = data(:,2); % Current Data
%errors
errU = 0.01.*ones(size(U));
errI = 0.01.*ones(size(I));
%plot
e = errorbar(I ,U , errU, errU, errI, errI, 'o', 'Color', color(file_j,:),'Marker','o', 'MarkerSize',6);
Legend{file_j}=(['T_' num2str(file_j) '=' Legends{file_j}]);
end
Error using load
Unable to find file or directory 'Kennlinien_1.txt'.
legend(Legend,'Location', 'Northwest');