MATLAB: Multiple Criteria Look-Up Function within MATLAB

criteriaMATLABmatrixmultipletablevlookup

I would like to recreate the following VLOOKUP function within Matlab for multiple criteria:
For those unfamiliar with the EXCEL function, you essentially have to create a meta data column concatenating columns 1 & 2, that value is then used to lookup the corresponding value in the DIM 3 column.
Thanks in advance.

Best Answer

If the data are defined as:
d1=repmat([2:5],5,1); d1=d1(:);
d2=repmat(1:5,1,4);d2=d2(:);
d3=100:100:2000;d3=d3(:);
then the lookup function can be defined as
fnVLU=@(i1,i2) d3(all([i1 i2]==[d1 d2],2));
Example:
>> fnVLU(3,4)
ans =
 900
>>
Above includes the specific table in the function; if they change routinely then the table can also be arguments.
ADDENDUM
An alternate if the lookup values are always constructed as shown...
N1=max(d2);       % size of subtable
fnIX=@(i1,i2) N1*(i1-d1(1))+d2(i2);
>> fnIX(3,4)
ans =
   9
>> d3(ans)
ans =
 900
>>
ADDENDUM
The actual problem is very far removed from the illustration so I'll leave it for pedagogical purposes.
For the last set of code that has issues outlined in comments below, a functional implementation awaiting resolution of those issues would look like (from the point onward I made a change)--
    ...
    % Use NaN to show missing locations more clearly...  
    ...    
    Table = [1:10;1:10;100:100:1000];
    % Define lookup function for the table -- NB: it's now horizontal
    fnL=@(SI,K) Table(3,all(Table(1:2,:)==[SI; K]));
    for i=1:length(D_Outer)
      for j=1:length(Pitch)
        for k=1:length(Free_Length)
          for q=1:length(D_Wire)
            if strcmp(Spring_Type,'Open');
              Pitch(k) = (Free_Length(k) - D_Wire(q))/A_Coils;
            elseif strcmp(Spring_Type,'Open and Ground');
              Pitch(k) = Free_Length(k)/Tot_Coils;
            elseif strcmp(Spring_Type,'Closed');
              Pitch(k) = (Free_Length(k) - (3*D_Wire(q)))/A_Coils;
            elseif strcmp(Spring_Type,'Closed and Ground');
              Pitch(k) = (Free_Length(k) - (2*D_Wire(q)))/A_Coils;
            end
            Factor_K(k) = Pitch(k)/D_Wire(q);    
            Spring_Index(i) = D_Outer(i)/D_Wire(q);  
            % with above table there are many points for which 
            % there won't be a match and fnL() will return an
            % empty result.  Enclose in try...catch block to not crash
            % Preallocated Factor_L to NaN so they'll show up clearly
            try
              Factor_L(i)=fnL(Factor_K(k),Spring_Index(i));
            catch
              Factor_L(i)=0;  % so will show which didn't match
            end
          end
        end
      end
    end
Owing to the lack of points intersecting in the table and the issue with overwriting the indices in the result vectors, this yields less than satisfying result of
>> [[Spring_Index nan(1,5)];Factor_K;[Factor_L nan(1,5)]]
ans =
    2.0000    4.0000    6.0000    8.0000   10.0000   12.0000   14.0000   16.0000   18.0000   20.0000       NaN       NaN       NaN       NaN       NaN
         0    0.5000    1.0000    1.5000    2.0000    2.5000    3.0000    3.5000    4.0000    4.5000    5.0000    5.5000    6.0000    6.5000    7.0000
         0         0         0         0         0         0         0         0         0         0       NaN       NaN       NaN       NaN       NaN
>>
in that no results were saved that had intersecting values in Table
I added another diagnostic display just to illustrate the code itself functions properly and that it's the data and indexing issues that are the problem where output
disp([i k Factor_K(k),Spring_Index(i) Factor_L(i)])
in the try block so could see the successes overall in the loop besides just the failures that finally were saved. That resulted in
>> jsmith
     i     k    F_K   SI   F_L  % added header for column ID -- dpb
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     1     5     2     2   200
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     2     9     4     4   400
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
     3    13     6     6   600
>>
This illustrates clearly the over-storing into i, k indices that are repeated and that only the locations in the Table with same values match as presently constructed.
But, the lookup works as supposed to; it's just that there's no data available for almost all the cases.
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