match IDs + find a number within a matrix in Matlab - matlab

Question

I am facing a problem in matching elements in 2 matrices. The first element can be matched using ismember but the second element should be within a range. Please see the example below:
% col1 is integerID, col2 is a number. -->col1 is Countrycode, col2 is date
bigmat = [ 600 2
600 4
800 1
800 5
900 1] ;
% col1 is integerID, col2 is VALUE, col2 is a range -->value is Exchange rate
datamat = {...
50 0.1 [2 3 4 5 6] % 2:6
50 0.2 [9 10 11] % 9:11
600 0.01 [1 2 3 4] % 1:4
600 0.2 [8 9 10] % 8:10
800 0.12 [1] % 1:1
800 0.13 [3 4] % 3:4
900 0.15 [1 2] } ; % 1:2
I need the answer as:
ansmat = [ 600 2 0.01
600 4 0.01
800 1 0.12
800 5 nan % even deleting this row is fine
930 1 0.15 ] ;
For simplicity:
All intIDs from matrix_1 exist in matrix_2.
The numbers in range are dates! Within a range, these numbers are consecutive: [1 2...5]
For any ID, dates in the next row are not continuous. Eg, you can see [1 2 3 4] and then [8 9 10] in next row.
bigmat is a huge matrix! 300,000-500,000 rows and so a vectorized code would be appreciated. datamat is roughly 5000 rows or less. You can convert the cell to matrix. For each row, I have the minimum and maximum. The 3 column is minimum:maximum. Thanks!

Answer 1

Here is one possible implementation:
%# data matrices
q = [
600 2
600 4
800 1
800 5
900 1
];
M = {
50 0.1 [2 3 4 5 6]
50 0.2 [9 10 11]
600 0.01 [1 2 3 4]
600 0.2 [8 9 10]
800 0.12 [1]
800 0.13 [3 4]
900 0.15 [1 2]
};
%# build matrix: ID,value,minDate,maxDate
M = [cell2num(M(:,1:2)) cellfun(#min,M(:,3)) cellfun(#max,M(:,3))];
%# preallocate result
R = zeros(size(M,1),3);
%# find matching rows
c = 1; %# counter
for i=1:size(q,1)
%# rows indices matching ID
ind = find( ismember(M(:,1),q(i,:)) );
%# out of those, keep only those where date number is in range
ind = ind( M(ind,3) <= q(i,2) & q(i,2) <= M(ind,4) );
%# check if any
num = numel(ind);
if num==0, continue, end
%# extract matching rows
R(c:c+num-1,:) = [M(ind,1) repmat(q(i,2),[num 1]) M(ind,2)];
c = c + num;
end
%# remove excess
R(c:end,:) = [];
The result as expected:
>> R
R =
600 2 0.01
600 4 0.01
800 1 0.12
900 1 0.15

Answer 2

I'm not completely sure I understand .. should the second entry be '600 4 0.02'?
Anyways, you may be able to try something like:
% grab first column
col = bigmat(:, 1);
% find all entries in column that are equal to ID
rel = (col == id);
% retrieve just those rows
rows = bigmat(rel, :);
Then once you have the rows you need from your matrices, you can concatenate them together like so:
result = [rowsA(1:3) rowsB(2) rowsC(5:6)];