Stuck in endless loop

Hi all,

I am learning matlab thru practice and patience. I am trying to create a loop to get the mean of a precipitation dataset with a 0.5 grid spacing and dimensions x=141, y=71 and t =38. I am trying to build a structure to get the means per grid over each layer (38). I am running the following code but matlab is stuck in a endless loop. Is there any way to fix this to avoid getting stuck? Thanks in advance for your help

for t=1:38
    for x=1:141
        for y=1:71
            meanprecip(y,x,t)=nanmean(rain(y,x,t))
        end
    end
end

[Geoff Hayes]

Emmanuel - the code is probably not getting stuck in an endless loop since your for loops are well defined. The problem could be that the code is just slow. Try pre-sizing your meanprecip array since you know the dimensions of it:

meanprecip = zeros(38,141,71);
for t=1:38
    % etc.
end

You may be able to optimize your code and remove some one (or more?) loops. I haven't downloaded your rain data, but what does rain(y,x,t) return? Is it a scalar or an array? If a scalar, what does nanmean do for this single value?

[desert_scientist90]

This data is supossed to display a map when using Pcolor. Since is satellite data nan represents points over the ocean. Nanmean is to ignore the nan in the dataset.

[Geoff Hayes]

So is rain(y,x,t) a scalar? I think it might be and so your first layer is rain(:,:,1), a 71x141 2D array. Do you really want to calculate the nanmean of this 2D array? Or a row or column?

[desert_scientist90]

Yes is a scalar, I am trying to get the means over the years exm mean of 1979, 1980,1981..ect. to calculate the z-scores and then identify low and high values. To create a new map with the differences.

[Geoff Hayes]

So if it is a scalar, then you are not calculating the mean over a set of years...just a single value. Which dimension represents years?

[desert_scientist90]

t=38 represents the years.

Answer 1

[Siriniharika Katukam]

Hi,

As per my understanding, you are trying to find the mean of grid at each layer. In your case, if the output of rain(y,x,t) is a scalar, then calculating mean of a scalar is like reassigning. It is similar to

meanprecip(y,x,t) = rain(y,x,t);

If you want to calculate the mean of the grid at each year,

Try this:

for t=1:38
    meanprecip(t) = mean(rain(:,:,t))
end

Moreover, your code is not an endless loop.