Vector of dates going back one rolling year

I need to generate a rolling 1 year list of dates. I've tried using:

A=datevec(now);
DList=datenum(A(1), A(2):-1:A(2)-12, eomday(A(1), A(2)));

which will make the list I want as long as the current month is December, however it currently is not. So I get a list that goes back from November 2015 and then has multiple entries for Jan 2015 as it doesn't roll back to 2014.

Is there a straight forward way to get what I need? I don't have access to the financial toolbox so any of the functions included in it are out for me.

Thanks, Ben

Answer 1

[Stephen23]

You can subtract one from the year field:

>> Vend = clock;
>> Nend = datenum(Vend);
>> Nbeg = datenum([Vend(1)-1,Vend(2:end)]);
>> Nall = Nbeg:Nend;
>> Vall = datevec(Nall);

You might also want to adjust Nbeg by one, depending on whether you want to include start on the same date as the period ends on.

EDIT this code gives just first of each month, over the past twelve months (regardless of the end month):

>> Vend = clock;
>> Nbeg = datenum([Vend(1)-1,1+Vend(2),1]);
>> Vbeg = datevec(Nbeg);
>> Nall = datenum(Vbeg(1),Vbeg(2)+(11:-1:0),1);
>> datestr(Nall)
ans =
01-Nov-2015
01-Oct-2015
01-Sep-2015
01-Aug-2015
01-Jul-2015
01-Jun-2015
01-May-2015
01-Apr-2015
01-Mar-2015
01-Feb-2015
01-Jan-2015
01-Dec-2014

[Ben Anderson]

Stephen, This gives me every day going back one year. I only want a list of the last 12 months. I tried a few things on your code and couldn't seem to get it to do that.

I'd like a list like this:

>> datenum(2015,12:-1:1,1); datestr(ans)
ans=
01-Dec-2015
01-Nov-2015
01-Oct-2015
01-Sep-2015
01-Aug-2015
01-Jul-2015
01-Jun-2015
01-May-2015
01-Apr-2015
01-Mar-2015
01-Feb-2015
01-Jan-2015

But to be able to go back from the current month into last year if necessary.

Thanks

[Stephen23]

See my edited answer.

Answer 2

[Peter Perkins]

If you're using a recent version of MATLAB, try using datetime:

>> dateshift(datetime('today'),'end','month',-11:0)
ans = 
Columns 1 through 9
   31-Dec-2014   31-Jan-2015   28-Feb-2015   31-Mar-2015   30-Apr-2015   31-May-2015   30-Jun-2015   31-Jul-2015   31-Aug-2015
Columns 10 through 12
   30-Sep-2015   31-Oct-2015   30-Nov-2015

If need be, you can convertvert back to datenums afterwards.

[Ben Anderson]

I'm using R2013 currently (IT is trying to get us all upgraded to 2015) so I don't have dateshift sadly. If I did my problem would be solved!

[Peter Perkins]

Your original code is running into this, from the Carryover in Date Vectors and Strings doc page:

"Month values are an exception. MATLAB sets month values less than 1 to 1."

You could use addtodate in a loop, but see if this works for you:

>> A = datevec(now);
>> months = A(2):-1:A(2)-12;
>> years = A(1) - (months < 1)
years =
        2015        2015        2015        2015        2015        2015        2015        2015        2015        2015        2015        2014        2014
>> months = months + 12*(months < 1)
months =
    11    10     9     8     7     6     5     4     3     2     1    12    11
>> DList = datenum(years, months, eomday(years,months));
>> datestr(DList)
ans =
30-Nov-2015
31-Oct-2015
30-Sep-2015
31-Aug-2015
31-Jul-2015
30-Jun-2015
31-May-2015
30-Apr-2015
31-Mar-2015
28-Feb-2015
31-Jan-2015
31-Dec-2014
30-Nov-2014

Answer 3

[Thorsten]

A = datevec(now);
m = A(2) - [0:11];
y = repmat(A(1), 1, 12);

Find month that are in the previous years and set month and year accordingly:

idx = m < 1;
y = y - double(idx);
m(idx) = m(idx) + 12;

 for i=1:12, DList(i) = datenum(y(i), m(i), eomday(y(i), m(i))); end