how to use multiple colums to make graph (scatter) in Matlab

I want to make scatter plot suh that on left side plot using x1 and y1 values to make 1 point on left side and similar using x2 and y2 make a point on right side, Kindly help me with the code

for each row I want two points in graph

I have to do this process for the whole file ,

thanks

[Adam Danz]

What do you mean by 'left side' and 'right side'?

The image in your question has two sets of (x,y) coordinates. How would you like them to be separated? Two different axes?

Answer 1

[SuperNova]

I'm guessing that you want two plots on the same graph, and that you'd use different y axes to make a point. This answer assumes that is true.

First you need to import your data:

filename = 'YourData.csv';
delimiterIn = ',';
headerlinesIn = 1;
data = importdata(filename,delimiterIn,headerlinesIn); %you may want to export the Excel document as a .txt file first, those are easier

Then define your variables:

x1 = data(:,2); %the second column in your screenshot is the x1
y1 = data(:,3);
x2 = data(:,5);
y3 = data(:,6);

Now make your plot:

yyaxis left
plot(x1,y1) %you can also use scatter or whatever kind of graph you want to make
yyaxis right
plot(x2,y2)
yyaxis left
title('Plots with Different y-Scales')
xlabel('X')
ylabel('Y1')

yyaxis right
ylabel('Y2')

Also look here for more specifics: https://www.mathworks.com/help/matlab/creating_plots/plotting-with-two-y-axes.html

[Maleeha Khalid Khan]

thank u so much for your help, it means a lot

actually I want to two points, point p1 and p2, p1 has its x and y value and p2 has a seprate x and y value both are on the same graph p1 on the left and p2 on the right side

this image might help in understanding

[Adam Danz]

The image in your question lists many points. The comment above says you only want two points.

Each point has an (x,y) coordinate which is defined in the image in your question.

This is still very unclear.

[Maleeha Khalid Khan]

I want only two points p1 and p2

p1 should be on the left and it has its own x and y value coordinates

similary p2 should be on right and has its own x and y value coordinates

[Adam Danz]

So your quesiton is how to plot 2 points?

figure()
plot([-5,5], [1,2], 'bo')
ylim([-5 5])
xlim([-10,10])

[Maleeha Khalid Khan]

and how to apply loop so I can plot points for the whole file, for each row a graph should be plotted

[SuperNova]

You don't need a for loop for plotting points. In my original answer I defined variables of the data that you have. The computer is smart enough to take each (x,y) pair and plot them. All you need to do is tell the computer what the data are (define the variables).

Unless you actually want two plots for every row of data with one data point on each plot?

[Adam Danz]

Why is there so much discussion about right and left side? That's still not clear to me at all.

You have 2 sets of points. Is your goal merely to plot those points?

[Maleeha Khalid Khan]

no, I dont want two plots, I want a single plot for every row with 2 points on it (like scatter points)

[Maleeha Khalid Khan]

the reason of left and right side is that these points coorespond to an image

yes my goal is to plot these points, have to plot for every image and have data of 1400 images

[Maleeha Khalid Khan]

I have tried this code have made few chaging accordingly but its not working, any suggestions??

[Adam Danz]

After you import your data, all you have to do is,

plot(x1,y1) 
hold on
plot(x2,y2)

[Maleeha Khalid Khan]

tried this, its not working :(

[Adam Danz]

'not working" doesn't tell us anything. We can't see what you see and we don't know what your expected outcomes are.

[Maleeha Khalid Khan]

hope so now you can see, now it tells you a lot. I just want the two points , which are not plotted this is the output a blank plot with no points on it

[SuperNova]

Can you show us the code you used?

[Maleeha Khalid Khan]

thihs is what I want, graph like this with two points for each row value

[SuperNova]

Right, but did you define the x and y values properly? It would help us out if we could see your code and identify if there are any discrepancies

[Adam Danz]

Why do you need 2 y-axes?

Why doesn't this work?

figure()
plot(x1,y1) 
hold on
plot(x2,y2)

[SuperNova]

Yes, Adam's answer sounds like what you want. You'd have two datasets on one graph.

[Maleeha Khalid Khan]

this is code and output SuperNova, I have checked the x1,y1,x2,y2 tables hv values, but still not plotting points, kindly guide me

I need 2 y-axis one for left side point one for right side point Adam Danz

[Maleeha Khalid Khan]

I want one by one graph for every row values

[Adam Danz]

What is a one by one graph? Maybe you could draw what you want and share that image with us.

Also, what version of matlab are you using? yyaxis was introduced in r2016a.

[Walter Roberson]

Instead of mydata(:,3) use mydata{:,3} and likewise for the other items you assign to variables from mydata .

[Maleeha Khalid Khan]

Adam Danz, I mean one row should be plotted at a time then the second row and the rest, and i want to save each plot in jpeg format, I am using matllab r2017b

[Maleeha Khalid Khan]

Walter Roberson, thanks

[Walter Roberson]

Loop over the rows:

for r = 1 : size(y1,1)
    thisfile = sprintf('plot_%03d.jpg', r);
    thisx1 = x1(r,:);
    thisy1 = y1(r,:);
    plot(thisx1, thisy1);
    xlabel and ylabel and title and legend as appropriate
    pause(1) %give it time to render
    saveas(gcf, thisfile)
end

[Maleeha Khalid Khan]

thanks &

from every row there r 2 points like p1 and p2

p1 has its own x and y coordinates , p2 has sperate y coordinate

assume p1 has y axis on left and p2 has y axis on right, but same x axis

so how should I apply loop

[Walter Roberson]

When I compare that situation to the data you presented an image of, it looks to me as if p1 x and p1 y are scalars. If you plot those (and y2) in one plot, then you would only get a single dot, not a line. It also looks to me like p2 x is not the same as p1 x ?

[Maleeha Khalid Khan]

yes you are right its like this p1 and p3 hv different x value and y value but I want to plot them in same graph

[Walter Roberson]

for r = 1 : size(y1,1)
    thisfile = sprintf('plot_%03d.jpg', r);
    thisx1 = x1(r,:);
    thisy1 = y1(r,:);
    thisx2 = x2(r,:);
    yyaxis left
    h1 = plot(thisx1, thisy1, 'r*');
    xlabel('x')
    ylabel('y1')
    yyaxis right
    h2 = plot(thisx1, thisy2, 'b^');
    ylabel('y2')
    legend([h1, h2], {'x1', 'x2'});
    title( sprintf('row #%d', r) )
    pause(1) %give it time to render
    saveas(gcf, thisfile)
end