How do I create a vector with the first day of each month?
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How do I create a column vector with the first day of each month? Considering I have a list of days...
3 comentarios
Jan
el 27 de Abr. de 2013
And example in valid Matlab syntax would be more helpful. The input is still not clear. Something like this would be much easier to understand:
data = [datenum('10/01/1998'), datenum('06/31/1999')]
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John Doe
el 27 de Abr. de 2013
Editada: John Doe
el 27 de Abr. de 2013
Not quite sure what you are asking for here.
I assume you have a vector with all days from Monday-Sunday, and you know which day the first day of the year is:
weekdays = [{'Monday'},{'Tuesday'},{'Wednesday'},{'Thursday'},{'Friday'},{'Saturday'},{'Sunday'}];
dayNumber = zeros(1,12);
dayNumber(1) = 2; % 2013 started on a Tuesday.
numDays = [31 28 31 30 31 30 31 31 30 31 30 31]; % Not a leap year
for i = 1:11
dayNumber(i+1) = mod((dayNumber(i)+days(i)-1),7)+1;
end
for i = 1:12
dayName(i) = weekdays(dayNumber(i));
end
If you need to account for leap years: It is a leap year every fourth year, except years that can be divided by 100, except years that can be divided by 400.
A general approach would be something like this:
year = 2013;
year0 = 1900;
startDay = 1; % Year 1900 started on a monday.
if year > year0
for i = 1:(year-year0)
if mod((year0+i),4)~=0
startDay = startDay + 365;
elseif mod((year0+i),4)==0 && mod((year0+i),100)~=0
startDay = startDay + 366;
elseif mod((year0+i),4)==0 && mod((year0+i),100)==0 && mod((year0+i),400)~=0
startDay = startDay + 365;
elseif mod((year0+i),4)==1 && mod((year0+i),400)==0
startDay = startDay + 366;
end
end
end
dayNumber = mod(startDay,7)+1;
This gives dayNumber = 2, for year = 2013. Then continue with the code above. (numDays(2)=29, if leap year)
2 comentarios
Jan
el 27 de Abr. de 2013
@Robert: Nicer and more efficient:
weekdays = {'Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday'};
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Jan
el 27 de Abr. de 2013
indata = datenum('10/01/1998'):datenum('06/31/1999');
dvec = datevec(data);
duniq = unique(dvec(:, 1:2), 'rows');
result = datenum(v(:,1), v(:,2), 1);
Now result contains a row vector of the serial date numbers of the first day of each month contained in the input data.
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