[R] Date issues

[Santosh Srinivas]

I tried this and it works too (For most part) .... strangely for certain
dates (20090831) it is giving NA ...

> FnO_Data$Date[m:l]
 [1] 20090828 20090828 20090828 20090828 20090828 20090828 20090828 20090828
20090828 20090828 20090828 20090828
[13] 20090828 20090828 20090828 20090828 20090828 20090828 20090828 20090828
20090828 20090828 20090828 20090828
[25] 20090828 20090828 20090828 20090828 20090828 20090828 20090828 20090828
20090828 20090828 20090831 20090831
[37] 20090831 20090831 20090831 20090831 20090831 20090831 20090831 20090831
20090831 20090831 20090831 20090831
[49] 20090831 20090831 20090831
> as.Date(as.character(FnO_Data$Date[m:l]), format="%Y%M%d")
 [1] "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28"
"2009-09-28" "2009-09-28" "2009-09-28"
 [9] "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28"
"2009-09-28" "2009-09-28" "2009-09-28"
[17] "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28"
"2009-09-28" "2009-09-28" "2009-09-28"
[25] "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28" "2009-09-28"
"2009-09-28" "2009-09-28" "2009-09-28"
[33] "2009-09-28" "2009-09-28" NA           NA           NA           NA
NA           NA          
[41] NA           NA           NA           NA           NA           NA
NA           NA          
[49] NA           NA           NA          
> sessionInfo()
R version 2.11.1 (2010-05-31) 
i386-pc-mingw32 

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United
Kingdom.1252   
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C

[5] LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] zoo_1.6-4

loaded via a namespace (and not attached):
[1] grid_2.11.1    lattice_0.18-8 tools_2.11.1  


-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: 18 September 2010 21:27
To: Santosh Srinivas
Cc: r-help at r-project.org
Subject: Re: [R] Date issues

On Sat, Sep 18, 2010 at 11:25 AM, Santosh Srinivas
<santosh.srinivas at gmail.com> wrote:
> Strangely this is not working ... what am I doing wrong here?
>
>> tDate <- FnO_Data$Date[1]
>> tDate
> [1] 20090101
>> as.Date(c(tDate),format="%Y%m%d")
> [1] NA
>

Do you have zoo loaded?  If you do then a minimal reproducible example
(see last line of every message to r-help) is:

> library(zoo)
> as.Date(20090101, format = "%Y%m%d")
[1] NA

Note that numeric arguments here are treated as the number of days
since the Epoch and not as yyyymmdd.  As others have pointed out this
works:

> as.Date(as.character(20090101), format = "%Y%m%d")
[1] "2009-01-01"

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