Inserting zeros for missing values in a vector
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% ID is an index
% IDx is a 'result' (Values in Vx conform to IDx)
% Index values 1 and 4 and missing in IDx (when compared with ID)
% I want to put a zero in Vx at positions 1 and 4
% This code works - newVx has zeros in right places
ID=[1:5]';
IDx=[2,3,5]';
Vx=[10,15,20]';
newVx=NaN( size( ID ) );
newVx (ismember(ID,IDx)) = Vx;
newVx = fillmissing(newVx,'constant',0)
%
% but if the problem is repeated (below)
% I get an error message:
% Unable to perform assignment because the left and right sides have a different number of elements.
%
ID=[1:5]';
ID2=repmat(ID,2,1);
IDx=[2,3,5,1, 4]';
Vx=[10,15,20, 30, 40]';
newVx=NaN( size( ID2 ) );
newVx (ismember(ID2,IDx)) = Vx;
newVx = fillmissing(newVx,'constant',0)
%
% In this case newVx should look like this:
% ID newVx
% 1 0
% 2 10
% 3 15
% 4 0
% 5 20
% 1 30
% 2 0
% 3 0
% 4 40
% 5 0
%
% Appreciate suggestions for a solution - my ID vector is of length 97 and is repeated 15 times(1455 x 1)
% Length of (IDx &) Vx is 1208
2 Comments
Jon
on 4 Apr 2023
You could do this:
% define number of products
numProducts = 5;
% Define products and there export values
products = [2,3,5,1,4]
value = [10,15,20,30,40];
% Assume that when product list goes to a lower value we are on to the next
% country, then assign corresponding row index in full matrix
country = cumsum([1 diff(products)<0])% gives country number
rowIdx = (country-1)*numProducts + products;
% Make output data array with first column product id's second column
% export value
numCountries = max(country);
exportValues = zeros(numCountries*numProducts,2);
expValues(:,1) = repmat((1:numProducts)',2,1); % product id's
expValues(rowIdx,2) = value
Jon
on 4 Apr 2023
Please note the above solution will not work if you have some countries that do not export anything, as there will be no way to detect that there is a missing country in your products vector. If you have to cover this edge case then further development will be required
Accepted Answer
Jon
on 3 Apr 2023
At line 22 on the right hand side you have the vector Vx which has 5 elements. On the left hand side you have newVx indexed by ismember(ID2,IDx). Evaluating ismember(ID2,IDx) you see that it is true for all 10 elements of ID2. So you are trying to assign a 5 element vector to a 10 element vector and MATLAB can't do that, thus the error.
7 Comments
Jon
on 6 Apr 2023
Your welcome, interesting problem. If this solved your problem could you please accept the answer. This way if someone else has a similar issue they will know that a solution is available.
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