Interpolation of temperature with pressure
12 views (last 30 days)
Show older comments
Hi all,
as a newbie in Matlab, I've got a simple problem :
1) I have two dataset of pressure and temperature which both have a length of 1000
2) There are some missing data in my temperature profile, I'd like to interpolate around these missing values
3) I use interp1(temperature,pressure) -> it doesn't interpolate (no error message)
Why ?
Thank you for your help ! Florian
0 Comments
Answers (2)
Star Strider
on 8 Apr 2014
You have to tell it at what value of what variable you want to interpolate your data. (Your call to interp1 needs a third argument.)
2 Comments
Star Strider
on 8 Apr 2014
Edited: Star Strider
on 8 Apr 2014
I don’t know what your data look like, so I generated my own. You may have to adapt this to your situation. You can trace it through to see how it functions.
This seems to be a solution:
% Create data —
x = 0:0.1:2*pi;
y = sin(x);
% Create NaNs in data —
yn = y;
xn = x;
xn(5:5:end) = NaN;
yn(5:5:end) = NaN;
% Convert NaNs to missing values —
xm = xn;
ym = yn;
ym(isnan(ym)) = [];
xm(isnan(xm)) = [];
% Find indices of NaNs and interpolate for missing ‘x’ values —
ixn = find(isnan(xn));
for k1 = 1:size(ixn,2)
ixr = [xn(ixn(k1)-1) xn(ixn(k1)+1)];
xi(k1) = mean(ixr);
end
% Use interpolated ‘x’ values to interpolate missing ‘y’ values —
yi = interp1(xm, ym, xi);
figure(1)
plot(xn, yn, 'ob')
hold on
plot(xi, yi, '+r')
hold off
grid
(Apologise for the delay. Out for a bit on errands.)
Kelly Kearney
on 8 Apr 2014
Assuming temp and pressure are your vectors, you need to use the non-missing values to interpolate the missing ones:
ismissing = isnan(temp);
temp(ismissing) = interp1(pressure(~ismissing), temp(~ismissing), pressure(ismissing));
0 Comments
See Also
Categories
Find more on Interpolation in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!