Combining matrices into one

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Joel Schelander
Joel Schelander on 11 Mar 2021
Edited: Jan on 15 Mar 2021
I have one vector denoting every minute of the year: T=[1:525600].'
I have a matrix containing 2 coulumns and 13777 rows(B). The first column describes the minute that a EV is charging, the second column describes how much is charged that minute.
What I need is a matrix that contains all the minutes of the year as well as the values from column 2 in B:
B=[3849 0.183333333333333
3850 0.183333333333333
3851 0.183333333333333
3852 0.183333333333333];
The matrix contains every minute of year as well as the values from B, if there is no value in B for a certain minute, that row in the second column should be 0.
Like this
[ 3847 0
3848 0
3849 0.18333
3850 0.18333
3851 0.18333
3852 0.18333
3853 0
3854 0]
I have tried for loops back and forth, but not sure how I can create this matrix.

Accepted Answer

Jan
Jan on 11 Mar 2021
T = (1:525600).';
B = [3849, 0.1833; ... % Different values to avoid confusion
3850, 0.1834; ...
3851, 0.1835; ...
3852, 0.1836];
match = ismember(T, B(:,1)); % Assuming that B is sorted
T(match, 2) = B(:, 2); % Fills other values with 0
  4 Comments
Jan
Jan on 15 Mar 2021
Replace
B=cell2mat(CAR(1));
by the more efficient:
B = CAR{1};
If B(:,2) has more elements than match, some of the times in B are not found in T or they exist multiple times. There is no general solution to handle this. Check which times are concerned:
T = (1:525600).';
[matchT, indexB] = ismember(T, B(:, 1));
% Show problems:
C = B;
C(indexB, :) = [];
disp('Missing:')
disp(C)
% Copy the matching values:
T(matchT, 2) = B(indexB, 2);

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