MATLAB: How to write all month’s last dates for a given period of time

Question

Hello guys. Well I have daily time series form 1990-2015

    % code
b=726867;
a=9125;
for i=1:a
    b=b+1;
    BigMatrix(i,1)=b;
end
 BigMatrix=cellstr(datestr(BigMatrix));

Now I want to make another variable where I have only last date of months for a same period of time.

Thanks in advance

Answer 1

Hi,

first of all: you don't need the loop

BigMatrix = b + (1:a);
BigMatrixStr = cellstr(datestr(BigMatrix));

For the last day of a month you have different possibilities. One is to use datevec and note, that the last day of a month is one day before the first of the next month:

% add one day and convert to date vectors:
BigMatrixVec = datevec(BigMatrix+1);
% remove all that are not the first of a month
BigMatrixVec(BigMatrixVec(:,3)~=1, :) = [];
% and subtract that one day again:
BigMatrixStrLast = cellstr(datestr(datenum(BigMatrixVec)-1));

Or use the datetime object that comes with R2014b:

dt = datetime(BigMatrix, 'ConvertFrom', 'datenum');
t = unique(dateshift(dt, 'end', 'month'));
% remove the last month if it's past the last dt
t(t>dt(end)) = [];

Titus