Using the new datetime structure within datasets

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Jesse Blocher
Jesse Blocher 2015-2-24
评论： Jesse Blocher 2015-2-24
I have a dataset with date variables as datenums. I'd like to convert them to the new datetime datatype. Here is what I did:
ds.newdate = datetime(ds.olddate,'ConvertFrom','datenum');
This is what I get:
ds
ans =
olddate newdate
734138 [1x1 datetime]
This isn't useful. What I want is this:
ds
ans =
olddate newdate
734138 31-Dec-2009
There is some sort of sub-indexing going on where I have to go another level deeper to access my date variable. How do I access it directly in the dataset?

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采纳的回答

Peter Perkins
Peter Perkins 2015-2-24
Jesse, have you tried using a table rather than a dataset? A table is, roughly speaking, a replacement for dataset that is available in core MATLAB (rather than just the Statistics Toolbox) since R2013b. Since you are using datetime, you must have R2014b.
The [1x1 datetime] that you are seeing is really just a display artifact, and ds.newdate is a datetime. But table provides the display you are looking for:
>> t = table((734138:734140)','VariableNames',{'OldDate'})
t =
OldDate
__________
7.3414e+05
7.3414e+05
7.3414e+05
>> t.NewDate = datetime(t.OldDate,'ConvertFrom','datenum')
t =
OldDate NewDate
__________ ____________________
7.3414e+05 31-Dec-2009 00:00:00
7.3414e+05 01-Jan-2010 00:00:00
7.3414e+05 02-Jan-2010 00:00:00
Hope this helps.
  1 个评论
Jesse Blocher
Jesse Blocher 2015-2-24
Great! I didn't even know about tables. I had been using datatables for a while and must have missed that new structure.

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