date objects

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Hi Erin,

"Best" is subjective, but I like

library(lubridate)
library(plyr)
xb.df <- mutate(xb.df,
                time = ymd(time, truncated = 1),
                year = year(time),
                quarter = quarter(time))

Best,
Ista
Hello!

I  generate the following two data frames:

xa.df <- data.frame(x=rnorm(10),time=2001:2010)
xa.df
             x time
1  -1.73207086 2001
2  -0.84014049 2002
3  -0.02332163 2003
4  -1.47236670 2004
5  -0.17736265 2005
6  -1.27134314 2006
7  -2.53425374 2007
8   0.79132952 2008
9   1.16574188 2009
10  1.99660600 2010
tim1 <- c("2010-01","2010-02","2010-03","2010-04","2011-01","2011-02",
+ "2011-03","2011-04")
xb.df <- data.frame(y=rnorm(8),time=tim1)
xb.df
           y    time
1 -1.5175587 2010-01
2  1.2035292 2010-02
3 -0.7313063 2010-03
4 -1.5544370 2010-04
5 -0.5907269 2011-01
6  1.0634754 2011-02
7  0.9029293 2011-03
8  0.5996780 2011-04

What is the best way to turn the time columns into date objects (annual and
quarterly)?

Thanks,
Erin

--
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

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