Matlab do not regress if any Y is zero in loop - matlab

Question

I am using regress to perform linear regression on a large nc file (containing lat, lon, time, and temperature). So for each lat, lon, temperature is regressed over 30 years (one measurement each year).
In some years, some temperatures are 0 K, in those cases I want the loop to not regress, so the final mean slope does not include these.
Below is the important part of my code.
I am not getting an error but also not getting any difference in whether i include y(y==0) = NaN;, so I think there may be a better way. I had understood that regress ignores these automatically, but that also appears to not be the case.
% initialise time parameters
time_begin = [1981, 1, 1, 0,0,0];
time_end = [2010,12,31,23,0,0];
years = (time_begin(1):time_end(1))';
nyears = length(years);
% create storage and regress
TXx = randi(100, 288, 192, 30);
lat = rand(192, 1);
lon = rand(288, 1);
time = rand(30,1);
M = numel(lon);
N = numel(lat);
slope = zeros(M, N);
intercept = zeros(M, N);
T = numel(time);
x = ([ones(T, 1) years]);
% Regress each lat/lon location
for i = 1 : M
for j = 1 : N
% Get all time instances of each lat/lon location
y = squeeze(TXx(i, j, :));
y(y==0) = NaN;
% Create regression problem and solve
c = regress(y, x);
intercept(i, j) = c(1);
slope(i, j) = c(2);
end
end

Answer 1

The NaN's are being ignored, but not in the way you want... The individual data points are ignored, not the entire data set, and thus still a regression is made.
You could simply add a simple check using an if statement,
for i = 1 : M
for j = 1 : N
% Get all time instances of each lat/lon location
y = squeeze(TXx(i, j, :));
if ~any(y==0)
% Create regression problem and solve
c = regress(y, x);
intercept(i, j) = c(1);
slope(i, j) = c(2);
end
end
end