How to rank 3d matrix across 2 dimensions

Hi Everyone,

I have 5 variables of gridded data that are identical in size (361x181 matrices). I have run these through different scenerios for my anaylsis and now am trying to compare the changes. What I would like to do is create a 3-d matrix of all the variables sorted by highest to lowest (361x181x5) but retain the "name" of the vairable so I can say this variable had the most change at this location.

From what I have been able to find online the best way seems to be to create a cell of off the variables and then sort.

https://www.mathworks.com/matlabcentral/answers/524243-sort-variables-form-lowest-to-largest-but-by-keeping-their-name

https://www.mathworks.com/matlabcentral/answers/526297-sorting-variables-by-value

The issue i am having is sorting the cell along the correct dimesions with the associated names. See the code I've tried so far below, the variables are attached

iVars = zeros(361,181,5);
iVars(:,:,1) = var1;
iVars(:,:,2) = var2;
iVars(:,:,3) = var3;
iVars(:,:,4) = var4;
iVars(:,:,5) = var5;
iNames = {'Var 1','Var 2','Var 3','Var 4','Var 5'};

[~,VarSORT]=sort(iVars,3,'descend');
iNames(VarSORT);

Any help or suggestions is greatly appreciated!

[Matt J]

What is wrong with your current code?

[James Spalding]

i get the following warning message:

"The opperation or expression 'iNames(VarSORT);' has no evident effect."

And when I look at the iNames variable in the workspace it is just a 1x5 cell with the single string of text in each cell.

I think what I need to do is get Names vairable so that it is either a 361x181 cell where at each cell location it is either a table or string array of the 5 vairable names - but I still haven't figured that out either.

Thanks

James

[James Spalding]

For clarity, my end goal is to have either a cell-like strucutre that is 361x181, and in each cell value it will have a list/table ranking the initial values from the 5 variables at every index (decending order).

So for example "finalRank" (10,10) will have a list of the associated names in decending order of the values from var1(10,10) var2(10,10) var3(10,10) var4(10,10) and var5(10,10).

If possible it would be nice to have the associated values in ranked order too but tha tis less critical to me

Thanks

James

[James Spalding]

Hi all,

So i have found a "forced" solution for this problem that takes a while but does work (see code below)

If anyone can come up with a better solution that doesn't run the risk of my computer suddenly bursting into flames let me know I'd appreciate it!

James

%rank vars in single variable
iVars = zeros(361,181,5);
iVars(:,:,1) = var1;
iVars(:,:,2) = var2;
iVars(:,:,3) = var3;
iVars(:,:,4) = var4;
iVars(:,:,5) = var5;
VarsRank=cell(361,181);

for j = 1:361
    for k = 1:181
val1=table(iVars(j,k,1),"Var1");
val2=table(iVars(j,k,2),"Var2");
val3=table(iVars(j,k,3),"Var3");
val4=table(iVars(j,k,4),"Var4");
val5=table(iVars(j,k,5),"Var5");
irnk=[val1;val2;val3;val4;val5];
RNK=sortrows(irnk,1,'descend');

VarsRank{j,k}=irnk;
fprintf("on iteration\n")
t=j*k;
disp(t)
fprintf('of 65341')
    end
end

Answer 1

[Matt J]

Is this (simplified) not what you want?

iVars=rand(3,3,5);
iNames = {'Var 1','Var 2','Var 3','Var 4','Var 5'};

[~,VarSORT]=sort(iVars,3,'descend');
iNames=iNames(VarSORT)

iNames = 3×3×5 cell array
iNames(:,:,1) = 

    {'Var 5'}    {'Var 4'}    {'Var 1'}
    {'Var 2'}    {'Var 1'}    {'Var 1'}
    {'Var 4'}    {'Var 3'}    {'Var 3'}


iNames(:,:,2) = 

    {'Var 2'}    {'Var 1'}    {'Var 4'}
    {'Var 5'}    {'Var 3'}    {'Var 4'}
    {'Var 2'}    {'Var 5'}    {'Var 5'}


iNames(:,:,3) = 

    {'Var 1'}    {'Var 3'}    {'Var 5'}
    {'Var 3'}    {'Var 2'}    {'Var 2'}
    {'Var 5'}    {'Var 1'}    {'Var 1'}


iNames(:,:,4) = 

    {'Var 4'}    {'Var 5'}    {'Var 3'}
    {'Var 1'}    {'Var 5'}    {'Var 5'}
    {'Var 3'}    {'Var 4'}    {'Var 2'}


iNames(:,:,5) = 

    {'Var 3'}    {'Var 2'}    {'Var 2'}
    {'Var 4'}    {'Var 4'}    {'Var 3'}
    {'Var 1'}    {'Var 2'}    {'Var 4'}

Answer 2

[Bruno Luong]

iNames(VarSORT);

won't change iNames, you need to assign the expression to a variable VarsRank

iVars = zeros(361,181,5);
iVars(:,:,1) = var1;
iVars(:,:,2) = var2;
iVars(:,:,3) = var3;
iVars(:,:,4) = var4;
iVars(:,:,5) = var5;
iNames = {'Var 1','Var 2','Var 3','Var 4','Var 5'};
[~,VarSORT]=sort(iVars,3,'descend');
VarsRank = iNames(VarSORT); % Assign the result to a variable