Using Interp1 when data has duplicates

Hi,

I am working with Timeseries data. Time vs Population in a building. I have data from two different sources for the space population. The plot is shown in the image attached. I need to interpolate these two plot lines to identify Y(population) values from both sources at regular intervals of X(Time) values (i.e. Population at 1-min increment in time). I tried interp1 but both my data sources have duplicates (as my population changed multiple times within a min). The time steps for both data sources dont match in the original data. I need to keep the duplicates as they are required data points. I am not sure how to work around this issue to obtain Y values from both sources at the same time-steps.

PS: I used clear 'x' and 'y' values and then reobtain x and y values but it only gives me the same data points that I used to plot.

Thanks for the help.

[Kevin Phung]

Is taking the average of the duplicates an option?

[Krishna Chaitanya Simma]

Sometimes, the space is vacated within a min. So the population fall from 38 to 7 within a min giving me about 10 data points within that min. I am not sure if averaging is the best way to deal with it.

[Kevin Phung]

ok, but just to clarify, you want one line to describe both of those plots correct?

[Krishna Chaitanya Simma]

I added a picture for what I am trying to do. From the two plot lines, I want to divide the time (x-axis) into multiple equal steps and interporlate the Y values (both y1 and y2). And then, since time becomes constant for Y values from both sources, I want to plot them against each other as shown in the diagram below in the image posted. (ex: y1 vs y2).

Did I explain it clearly?

Answer 1

[Krishna Chaitanya Simma]

The following code worked. Incase anyone has similar issues. Instead of intrerp1, I used griddedInterpolant.

M = csvread('rdata24.csv');               % Read the data file for wifi routers
x1 = M(:,1);
y1 = M(:,2);
N = csvread('cdata24.csv');               % Read the data file for people counters
x2 = N(:,1);
y2 = N(:,2);

figure(1)
plot(x1,y1,x2,y2)

[x2,al,idx] = unique(x2,'stable');        % identify the non duplicate values 
y2 = y2(al);

hold on
F = griddedInterpolant(x2,y2);
G = griddedInterpolant(x1,y1);

x1q = linspace(0,1,300);                % Generate points to interpolate 
y1q = G(x1q);
y2q = F(x1q);

hold on
plot(x1q, y1q, '*')
plot(x1q, y2q,'ro')
hold off 

figure(2)
scatter(y1q,y2q);

[Tehreem Syed]

Hey! I tried your methods but it's not working.

Attached you can see the snippet of my code.

Thank you :)