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date and time - Different results with DateRange and LeapYearsQ in Mathematica 9 and 10


With Mathematica 9.0 for Mac OS X x86 (64-bit) (January 24, 2013) one could use


DateRange[{2000}, {2010}, "Year"]

to achive


{{2000}, {2001}, {2002}, {2003}, {2004}, {2005}, {2006}, {2007}, {2008}, {2009}, {2010}}

or


leapyears = Select[DateRange[{2000}, {2020}, "Year"], LeapYearQ[#] &]


with the result


{{2000}, {2004}, {2008}, {2012}, {2016}, {2020}}

With Mathematica 10.0 for Mac OS X x86 (64-bit) (June 29, 2014)


DateRange[{2000}, {2010}, "Year"]

one will get


{{2000, 1, 1}, {2001, 1, 1}, {2002, 1, 1}, {2003, 1, 1}, {2004, 1, 
  1}, {2005, 1, 1}, {2006, 1, 1}, {2007, 1, 1}, {2008, 1, 1}, {2009, 

  1, 1}, {2010, 1, 1}}

leapyears = Select[DateRange[{2000}, {2020}, "Year"], LeapYearQ[#] &]


{{2000, 1, 1}, {2004, 1, 1}, {2008, 1, 1}, {2012, 1, 1}, {2016, 1, 
  1}, {2020, 1, 1}}

The Function DateObject does not clear a bean to me


DateRange[DateObject[{2000}], DateObject[{2012}], "Year"]

enter image description here



So, how can i get rid of the additional month, day information on V10, i.e. using leapyears and DateObject returning Year only?



Answer



I would use:


DateRange[{2000}, {2010}, "Year"][[All, {1}]]


{{2000}, {2001}, {2002}, {2003}, {2004}, {2005}, {2006}, {2007}, {2008}, {2009}, {2010}}

% ~Select~ LeapYearQ



{{2000}, {2004}, {2008}}

Note the {1} in the Part parameters; see Head and everything except Head?


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