How can i generate month and year strings for Datetime vectors?

How can i generate month and year concatenated strings for Datetime vectors?

E.g. i have vector ['01/Jan/2015';'01/Feb/2015'], how can i transform this into [201501; 201502] ?

Answer 1

[Star Strider]

This works:

DTV = datetime(['01/Jan/2015';'01/Feb/2015']);      % Create ‘datetime’ Object
Out = fix(yyyymmdd(DTV)/100)                        % Desired Output

Out =
      201501
      201502

[dpb]

Curious...how/who interprets

yyyymmdd(DTV)

?? There's some magic in a string of date format letters when used as a functional reference with a datetime object??? That seems truly bizarre.

[Star Strider]

‘Ours is not to reason why ...’

[dpb]

Man, what that must do to the JIT optimizer...no wonder the newer versions suffer in size/performance to incorporate such...

I've not found this documented; I did discover there's

dateType — Type of values in X
'datenum' | 'excel' | 'juliandate' | 'posixtime' | 'yyyymmdd' | ...

which would let the above fix() operation work w/o the reference if used the 'yyyymmdd' output type when creating the object. It doesn't say default there altho presume it would be 'datenum'???

ADDENDUM/ERRATUM

OK, I did a search and indeed TMW did actually write and include a function yyyymmdd -- who'd've'a thunk of such an animuhl...but, anyway, it's not so magical after all; "there's nothing to see here, please move on" just a momentary "huh?!" as hadn't seen the function reference and it's just bizzare enough I didn't think of it as an ordinary function name.

Answer 2

[dpb]

t = datetime(DateStrings,'InputFormat','dd/MMM/yyyy', ...
                         'Format','yyyyMM');

should do it (altho I don't have recent release to test...

OK, to actually convert to numerics,

str2num(datestr(datenum(['01/Jan/2015';'01/Feb/2015']),'YYYYmm'))

[Steven Niggebrugge]

Hi, thanks for this, but it won't do the trick. This will keep the format as DateTime, it only present the value in a different way (yyyyMM instead of dd-MM-yyyy). I was looking for a conversion into a string or number variable, with value (e.g.) '201502', so no DateTime format. Any ideas on this?

[dpb]

While surely have solved the problem long ere now, a more recent comment brought the thread to attention--

The above is precisely what S Strider's answer does...

Answer 3

[Shameer Parmar]

Hello Steven,

here is the code..

dateArray = ['01/Jan/2015';'01/Feb/2015'];

for i=1:size(dateArray,1)
date = dateArray(i,:);
dateSplit = regexp(date,'/','split');

switch dateSplit{2}
    case 'Jan'
        month = '01';
    case 'Feb'
        month = '02';
    case 'Mar'
        month = '03';
        .
        .
        .
        .
    case 'Dec'
        month = '12';    
end

newDate(i,:) = [dateSplit{3},month];

end

[Ayodele Ogunkoya]

Hello, I am new to matlab. I will like to create a monhtly loop. For example i will like to loop through each days of each months of the year so that i can save output of each month of the year

[dpb]

Better form would be to create a new question with specifics for you precise situation rather than bury a comment in an old thread expecting an answer.

If you have an array of datetime values, simply iterate. If that's not the problem/question, see above comment... :)

Answer 4

[Peter Perkins]

To create numbers use the Year and Month properties of a datetime

>> d = datetime+calmonths([1;2;3])
d = 
   03-Sep-2016 16:37:49
   03-Oct-2016 16:37:49
   03-Nov-2016 16:37:49
>> 100*d.Year + d.Month
ans =
      201609
      201610
      201611

or use SS's suggestion:

>> fix(yyyymmdd(d)/100)
ans =
      201609
      201610
      201611

To create strings you could just call num2str on that, or ...

>> cellstr(d,'yyyyMM')
ans =
    '201609'
    '201610'
    '201611'