[R] Convert Factor to Date

[Patrick Casimir]

This is large data set Spencer. What about when the dates change as below:


COL1    COL2
Jan-14  1-Aug-16
Feb-14  1-Aug-16
Mar-14  1-Aug-16
Apr-14  1-Aug-16
May-14  1-Aug-16
Jun-14  1-Aug-16
Jul-14  1-Aug-16
Aug-14  1-Aug-16
Sep-14  1-Aug-16
Oct-14  1-Aug-16
Nov-14  1-Aug-16
Dec-14  1-Aug-16
Jan-15  1-Aug-16
Feb-15  1-Aug-16
Mar-15  1-Aug-16
Apr-15  1-Aug-16
May-15  1-Aug-16
Jun-15  1-Aug-16
Jul-15  1-Aug-16
Aug-15  1-Aug-16
Sep-15  1-Aug-16
Oct-15  1-Aug-16
Nov-15  1-Aug-16
Dec-15  1-Aug-16
Jan-16  1-Aug-16
Feb-16  1-Aug-16
Mar-16  1-Aug-16
Apr-16  1-Aug-16
May-16  1-Aug-16
Jun-16  1-Aug-16
Jul-16  1-Aug-16
Aug-16  1-Aug-16
Sep-16  1-Aug-16
Oct-16  1-Aug-16






________________________________
From: R-help <r-help-bounces at r-project.org> on behalf of Spencer Graves <spencer.graves at effectivedefense.org>
Sent: Tuesday, August 22, 2017 2:49 PM
To: r-help at r-project.org
Subject: Re: [R] Convert Factor to Date



On 2017-08-22 1:30 PM, Patrick Casimir wrote:
> Dear R Fellows,
>
>
> I Have a dataset( data1) with 2 columns of date showing a class of factor. How to convert them to date? Then compare them, keep the greater date only in a new column. Using as.Date to change the class to Date but the data becomes NA.


       When I specified a format with the second date, I got the desired
behavior:


 > as.Date(factor('1-Nov-16'), '%d-%b-%y')
[1] "2016-11-01"
 > as.Date('Nov-16', '%b-%y')
[1] NA
 > as.Date(factor('Nov-16'), '%b-%y')
[1] NA
 > as.Date('Nov-16', '%b-%y')
[1] NA


       To convert the first column, I pasted "1-" in front:


as.Date(paste0('1-', factor('Nov-16')), '%d-%b-%y')


       Hope this helps.  Spencer

> Much Thanks
>
>
> COL1    COL2
> Apr-16  1-Nov-16
> May-16  1-Nov-16
> Jun-16  1-Nov-16
> Jul-16  1-Nov-16
> Aug-16  1-Nov-16
> Sep-16  1-Nov-16
> Oct-16  1-Nov-16
> Nov-16  1-Nov-16
> Dec-16  1-Nov-16
> Jan-17  1-Nov-16
> Feb-17  1-Nov-16
> Mar-17  1-Nov-16
> Apr-17  1-Nov-16
> May-17  1-Nov-16
> Jun-17  1-Nov-16
> Jul-17  1-Nov-16
> Aug-17  1-Nov-16
> Sep-17  1-Nov-16
>
>
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>
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