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# How do i know to which graph i'm plotting?

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Elias Unk on 20 Jul 2018
Commented: Walter Roberson on 21 Jul 2018
data1 = load('data1.mat')
data2 = load('data2.mat')
by doing `plot(val(1, :))` i have a graph but I don't know if it corresponds to data 1 or data 2 how can I choose the data in plots?
the second question is how can I concatenate data1 and data 2 basically let's say data1 is 1 2 3 and data2 is 4 5 6 the expected outcome would be :
1 2 3
4 5 6
then plot them both in the same figure?
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### Answers (3)

Nesha Wright on 20 Jul 2018
To concatenate then use the command 'cat', to plot both 'plot(catdata)' or use the command 'hold on' if you decide not to concatenate them but still want to plot both.
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Elias Unk on 20 Jul 2018
I want to draw the content of data1 and data2 on the same figure

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Walter Roberson on 20 Jul 2018
I think you missed a line of code connecting data1 and data2 to val ?
For your other part:
combined = [data1; data2];
plot(combined.')
When you ask to plot a 2D array, plot() prefers to plot by column. Your combined would have three columns, so if you had done
plot(combined)
you would get three lines.
I say "prefers" to plot by columns because when you pass an x, y pair,
plot(x, combined)
then if x is a vector then x and y will be automatically transposed if needed so that size(x,1) = size(y,1). For example, plot(1:3, combined) would notice that x was length 3 and would automatically transpose combined to match.
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Walter Roberson on 21 Jul 2018
Try
combined = [data1.data1; data2.data2];

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Image Analyst on 21 Jul 2018
If you assigned data1 to val, then plotting val would plot data1. If you assigned data2 to val, then plotting val would plot data2.
To plot both data1 and data2 on the same axes:
plot(data1, 'b*-', 'LineWidth', 2, 'MarkerSize', 10);
grid on;
hold on;
plot(data2, 'rs-', 'LineWidth', 2, 'MarkerSize', 10);
xlabel('Index', 'FontSize', 20);
ylabel('Value'FontSize', 20);
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