Two sets of data with two date ranges and y-axis values

Hello all

I have two sets of data in Excel which I have uploaded to Matlab.

I want to plot these data on one grpah as a line/scatter graph.

Data Set 1

This has days on the x axis from day1 to day 250.

The value on the y axis goes up to 20 metres. I want to put this on the left side of the plot which is standard.

Data Set 2

This also has days on the x axis but the data only starts on day 15 and also goes up to 250.

The value on this y-axis for this data goes from 90 - 200 metres. I want to put this on the right side of the plot (Command = yyaxis right?)

I want to plot these two on the same plot but Data Set 2 values should only start on day 10 of Data Set 1

How do I get the data points to line up correctly?

Like this :

plot

code

hold on

code

I'm not sure if I have explained this correctly so please let me know if you need more of an explanation.

Many thanks

Answer 1

[Star Strider]

Try this —

x1 = 1:250;
y1  = 20*sin(2*pi*x1/100) + 20 + randn(size(x1))*5;

x2 = 15:250;
y2 = cos(2*pi*x2/150)*60 + 150 + randn(size(x2))*10;

figure
yyaxis left
plot(x1, y1)
ylabel('Y1')
yyaxis right
plot(x2, y2)
xl = xline(15,'--k', '‘(x2,y2)’ Start Time');
xl.LabelVerticalAlignment = 'bottom';
xl.LabelHorizontalAlignment = 'center';
ylabel('Y2')
grid
xlabel('X')

EDIT — (6 Mar 2024 at 19:02)

Added xline call to emphasize when ‘(x2,y2)’ begins.

.

[BenSven]

Thank you.

This is the kind of graph that I am looking for.

I have however not been taught sin, cos or pi in MATLAB.

Is there an easier way to get the same result?

I am mostly interersted in how to get the Data Set 2 to start on Day 15 of Data Set 1

[Star Strider]

My pleasure!

I created the data using simple trogonometric functions simply to have something to plot. (I would have used your data if you had provided it. If you want to upload it so that I can plot it, use the ‘paperclip’ button next to the Σ button on the top toolstrip, and follow the instructions.)

The offset data will automatically be plotted correctly for the second (orange) data set ((x2,y2) in my code). I will add an xline call to my earlier plot to emphasize that it is plotted correctly.

[BenSven]

Thank you. I think I have figured it out.

Very much appreciated.

[Star Strider]

As always, my pleasure!

Answer 2

[Aquatris]

Something like this maybe:

% create dummy time and data vectors
t1 = datetime(2013,11,1,8,0,0); % define random start of time vector
t2 = datetime(2014,11,1,8,0,0); % define random end of time vector
t_data1 = t1:t2;            % time vector for data1
t_data2 = t_data1(120:end); % time vector for data2 that 
                            %   starts at a later date than time vector 1

data_1 = rand(length(t_data1),1)*20; % random data 1
data_2 = rand(length(t_data2),1)*200;% random data 2

% desired plot maybe?
yyaxis left
plot(t_data1,data_1,'b.') % plot data 1 with blue dots on left scale
ylabel('data 1')
yyaxis right
plot(t_data2,data_2,'r.') % plot data 2 with red dots on right scale
ylabel('data 2')
legend('data 1','data 2')

[BenSven]

Thank you very much for your help.