If Else Statement in For Loop

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Brian DeCicco
Brian DeCicco le 2 Sep 2021
Commenté : Brian DeCicco le 3 Sep 2021
Hello, I have a 1440,721,40 matrix called mag_strength. The first dimension is longitude, the second is latitude, and the third represents 40 time steps of data. I'm trying to create a for loop with an if / else statement embedded that will look at all the data at each time step of the 3rd dimension and keep all values >1 and replace all other values that don't meet the requirement to NaNs. My resulting matrix (of equal size) is named: Fronts. When I run the loop, I get all NaN values, when I know that I should get a mixture of NaNs and positve values greater than 1. Any ideas on what's going on?
Fronts = zeros(1440,721,40);
for F = 1:40
disp(F)
if mag_strength(:,:,F)>1
Fronts(:,:,F) = mag_strength(:,:,F);
else
Fronts(:,:,F) = NaN;
end
end

Réponse acceptée

Chunru
Chunru le 3 Sep 2021
n1 = 6; % 1440
n2 = 4; % 721
n3 = 2; % 40
mag_strength = randn(n1, n1, n3)
mag_strength =
mag_strength(:,:,1) = -0.8025 0.9344 1.7522 -0.0025 0.7267 0.4267 -0.7882 0.1544 -1.3793 -1.1197 1.3624 -0.3141 -0.7260 1.9888 1.1160 -1.9104 0.4341 -1.6269 1.6487 1.2641 -0.9046 -1.8453 -0.3283 0.8055 -0.7476 -0.2142 0.9903 0.0892 -1.5335 0.3169 0.5660 0.1052 -2.0026 -0.0124 0.9250 0.4308 mag_strength(:,:,2) = -0.2306 -0.0103 -1.3022 0.6091 -0.1025 2.0710 -0.1591 -0.1148 0.0871 -1.6085 -0.6099 0.9604 0.1962 -1.2370 0.1842 0.9875 -0.0267 0.5523 1.5947 -0.9226 1.1566 -0.1529 0.5219 -1.0731 0.4503 -0.5973 1.5207 0.2089 -0.3907 -0.8328 1.0511 0.7779 -0.3594 -0.0712 0.0253 -0.7505
Fronts = mag_strength;
Fronts(Fronts<=1) = nan;
Fronts
Fronts =
Fronts(:,:,1) = NaN NaN 1.7522 NaN NaN NaN NaN NaN NaN NaN 1.3624 NaN NaN 1.9888 1.1160 NaN NaN NaN 1.6487 1.2641 NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN Fronts(:,:,2) = NaN NaN NaN NaN NaN 2.0710 NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN 1.5947 NaN 1.1566 NaN NaN NaN NaN NaN 1.5207 NaN NaN NaN 1.0511 NaN NaN NaN NaN NaN
  1 commentaire
Brian DeCicco
Brian DeCicco le 3 Sep 2021
Thank you, this makes a lot more sense! I was really over complicating my approach here.

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