[R] Date extract Year

[Bert Gunter]

Please read ?as.Date carefully. Your argument appears to be numeric
(??)  and you do not seem to have specified an origin:

"as.Date will accept numeric data (the number of days since an epoch),
but only if origin is supplied."

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
Clifford Stoll




On Sat, Mar 7, 2015 at 5:49 PM, Steve Archambault <archstevej at gmail.com> wrote:
> Hi all,
>
> I am trying in vain to create a new object "Year" in my data frame from
> existing Date data. I have tried many different approaches, but can't seem
> to get it to work. Here is an example of some code I tried.
>
> date1<- as.Date(wells$Date,"%m/%d/%Y")
> wells$year<-as.numeric(format(date1, "%Y"))
>
> I am starting with data that looks like this.
>
>         ID  Date DepthtoWater_bgs test test2
> 1  BC-0004 41163           260.60    3     1
> 2  BC-0004 41255           261.65    4     2
> 3  BC-0003 41345           166.58    5     3
> 4  BC-0002 41351           317.85    6     4
> 5  BC-0004 41355           262.15    7     5
> 6  BC-0003 41438           167.55    8     6
> 7  BC-0004 41438           265.45    9     7
> 8  BC-0002 41443           317.25   10     8
> 9  BC-0002 41521           321.25   11     9
> 10 BC-0003 41522           168.65   12    10
> 11 BC-0004 41522           266.15   13    11
> 12 BC-0003 41627           168.95   14    12
> 13 BC-0004 41627           265.25   15    13
> 14 BC-0002 41634           312.31   16    14
> 15 BC-0003 41703           169.25   17    15
> 16 BC-0004 41703           265.05   18    16
> 17 BC-0002 41710           313.01   19    17
> 18 BC-0003 41795           168.85   20    18
> 19 BC-0004 41795           266.95   21    19
> 20 BC-0002 41801           330.41   22    20
> 21 BC-0003 41905           169.75   23    21
> 22 BC-0004 41905           267.75   24    22
> 23 BC-0002 41906           321.01   25    23
>
> Any help would be greatly appreciated!
>
>
> -Steve
>
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