[R] another date conversion

[Gabor Grothendieck]

Can't say exactly since B has not been defined in your
post but I think you are attempting to mix dates from
different representations/classes as suggested by:

> chron(2003)
[1] 06/27/75

chron represents dates as no. of days since this origin:

> chron(0)
[1] 01/01/70

while the pastecs function cited frepresents dates 
as year.fraction

Thus numbers near 2003 are near the beginning of 2003
to that pastecs function but they represents dates
in 1975 to chron since they are around 2003 days since 
01/01/70.




Date:   Mon, 22 Mar 2004 13:40:36 -0600 
From:   Erin Hodgess <hodgess at gator.uhd.edu>
To:   <r-help at stat.math.ethz.ch> 
Subject:   [R] another date conversion 

 
Dear R People
Here is an interesting problem:

> library(pastecs)
> a <- 1:100
> b <- daystoyears(a,datemin="1/1/2003",dateformat="m/d/Y")
> b
[1] 2002.999 2003.002 2003.005 2003.008 2003.010 2003.013 2003.016 2003.018 2003.021 2003.024 2003.027 2003.029 2003.032
[14] 2003.035 2003.038 2003.040 2003.043 2003.046 2003.049 2003.051 2003.054 2003.057 2003.060 2003.062 2003.065 2003.068
[27] 2003.070 2003.073 2003.076 2003.079 2003.081 2003.084 2003.087 2003.090 2003.092 2003.095 2003.098 2003.101 2003.103
[40] 2003.106 2003.109 2003.112 2003.114 2003.117 2003.120 2003.123 2003.125 2003.128 2003.131 2003.133 2003.136 2003.139
[53] 2003.142 2003.144 2003.147 2003.150 2003.153 2003.155 2003.158 2003.161 2003.164 2003.166 2003.169 2003.172 2003.175
[66] 2003.177 2003.180 2003.183 2003.185 2003.188 2003.191 2003.194 2003.196 2003.199 2003.202 2003.205 2003.207 2003.210
[79] 2003.213 2003.216 2003.218 2003.221 2003.224 2003.227 2003.229 2003.232 2003.235 2003.238 2003.240 2003.243 2003.246
[92] 2003.248 2003.251 2003.254 2003.257 2003.259 2003.262 2003.265 2003.268 2003.270
> require(chron)
Loading required package: chron 

Attaching package 'chron':


The following object(s) are masked _by_ .GlobalEnv :

dates times 

[1] TRUE
> seq.dates(B,by="days",length=length(b))
[1] (06/26/75 23:59:01) (06/27/75 23:59:01) (06/28/75 23:59:01) (06/29/75 23:59:01) (06/30/75 23:59:01) (07/01/75 23:59:01)
[7] (07/02/75 23:59:01) (07/03/75 23:59:01) (07/04/75 23:59:01) (07/05/75 23:59:01) (07/06/75 23:59:01) (07/07/75 23:59:01)
[13] (07/08/75 23:59:01) (07/09/75 23:59:01) (07/10/75 23:59:01) (07/11/75 23:59:01) (07/12/75 23:59:01) (07/13/75 23:59:01)
[19] (07/14/75 23:59:01) (07/15/75 23:59:01) (07/16/75 23:59:01) (07/17/75 23:59:01) (07/18/75 23:59:01) (07/19/75 23:59:01)
[25] (07/20/75 23:59:01) (07/21/75 23:59:01) (07/22/75 23:59:01) (07/23/75 23:59:01) (07/24/75 23:59:01) (07/25/75 23:59:01)
[31] (07/26/75 23:59:01) (07/27/75 23:59:01) (07/28/75 23:59:01) (07/29/75 23:59:01) (07/30/75 23:59:01) (07/31/75 23:59:01)
[37] (08/01/75 23:59:01) (08/02/75 23:59:01) (08/03/75 23:59:01) (08/04/75 23:59:01) (08/05/75 23:59:01) (08/06/75 23:59:01)
[43] (08/07/75 23:59:01) (08/08/75 23:59:01) (08/09/75 23:59:01) (08/10/75 23:59:01) (08/11/75 23:59:01) (08/12/75 23:59:01)
[49] (08/13/75 23:59:01) (08/14/75 23:59:01) (08/15/75 23:59:01) (08/16/75 23:59:01) (08/17/75 23:59:01) (08/18/75 23:59:01)
[55] (08/19/75 23:59:01) (08/20/75 23:59:01) (08/21/75 23:59:01) (08/22/75 23:59:01) (08/23/75 23:59:01) (08/24/75 23:59:01)
[61] (08/25/75 23:59:01) (08/26/75 23:59:01) (08/27/75 23:59:01) (08/28/75 23:59:01) (08/29/75 23:59:01) (08/30/75 23:59:01)
[67] (08/31/75 23:59:01) (09/01/75 23:59:01) (09/02/75 23:59:01) (09/03/75 23:59:01) (09/04/75 23:59:01) (09/05/75 23:59:01)
[73] (09/06/75 23:59:01) (09/07/75 23:59:01) (09/08/75 23:59:01) (09/09/75 23:59:01) (09/10/75 23:59:01) (09/11/75 23:59:01)
[79] (09/12/75 23:59:01) (09/13/75 23:59:01) (09/14/75 23:59:01) (09/15/75 23:59:01) (09/16/75 23:59:01) (09/17/75 23:59:01)
[85] (09/18/75 23:59:01) (09/19/75 23:59:01) (09/20/75 23:59:01) (09/21/75 23:59:01) (09/22/75 23:59:01) (09/23/75 23:59:01)
[91] (09/24/75 23:59:01) (09/25/75 23:59:01) (09/26/75 23:59:01) (09/27/75 23:59:01) (09/28/75 23:59:01) (09/29/75 23:59:01)
[97] (09/30/75 23:59:01) (10/01/75 23:59:01) (10/02/75 23:59:01) (10/03/75 23:59:01)
> 




Why is it that the seq.dates values come back as 1975, please?
What am I doing wrong, please? (I'm sure it's something incredibly simple)

Thanks in advance!

R for Windows 1.8.1

Sincerely,
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: hodgess at gator.uhd.edu