How do I sum over multiple dimensions? I want my final result to be a average with respect to area not the number of grids.

When I use the sum command it sums the rows (A=sum(b)). I want a global average (emissions/space) as my final value and I keep getting a massive array. I need the sum of the first array divided by the sum of the second array. The first array is 4D.

Answer 1

[Image Analyst]

"I need the sum of the first array divided by the sum of the second array."

Try this:

ratio = sum(array4D(:)) / sum(otherArray(:));

None of us have any idea what you're talking about when you talk about grids, but you might check out the FAQ: https://matlab.wikia.com/wiki/FAQ#How_do_I_split_an_image_into_non-overlapping_blocks.3F or see the attached demos.

Answer 2

[Guillaume]

mean(yourarray(:))

No need to use sum to calculate the mean.

[Nesha Wright]

Wouldn't this solve by dividing by the number of grid squares? I need to divide by the sum of the values in the grid squares.

[Guillaume]

What grid squares?

I need to divide by ...

Need to divide what?

[Nesha Wright]

When the command mean is used on a gridded dataset it takes the sum of the array and divides it by the number of grid cell, I need to divide it by the sum area of the grid cells, not how many there are. I could be wrong...