R help - Apr 2006 - Problem using plot and converted dates

Dear R-help,
I am having problems with plotting converted dates in chronological as Mar-03,
May-03...Jul-04.
My script is:

sam4<-c("03/03/01","03/05/01","03/07/01","03/09/01","03/11/01","04/01/01","04/03/01","04/05/01","04/07/01")
sam5<-strptime(sam4,format="%y/%m/%d")
f<-data.frame(sam5,mkf)
plot(f,type="l")
# This works ok, but none of the labels appear on the x-axis, so I thought I
would convert them using
# as.POSIXct:

sam6<-format(as.POSIXct(sam5), "%b-%y")
mon<-factor(as.character(sam6),levels=sam6)
f2<-data.frame(mon,mkf)
plot(f2,type="l")

The problem is that plot(f2,type="l") no longer produces a line
plot...

Any help with this would be gratefully appreciated.

Best wishes,
Sion


--
Si?n Roberts

Department of Geography,
Queen Mary, University of London,
London,
E1 4NS.

Tel: +44 20 7882 5400
http://www.geog.qmul.ac.uk/postgraduate/student/roberts.html

Try:

y <- 1:length(sam4) # test data
dd <- as.Date(sam4, "%m/%d/%y")
plot(dd, y)

# also try this
library(zoo)
z <- zoo(y, dd)
plot(z)

Also read, from earlier today:

https://www.stat.math.ethz.ch/pipermail/r-help/2006-April/092471.html



On 4/17/06, s.e.roberts at qmul.ac.uk <s.e.roberts at qmul.ac.uk>
wrote:
> Dear R-help,
> I am having problems with plotting converted dates in chronological as
Mar-03,
> May-03...Jul-04.
> My script is:
>
>
sam4<-c("03/03/01","03/05/01","03/07/01","03/09/01","03/11/01","04/01/01","04/03/01","04/05/01","04/07/01")
> sam5<-strptime(sam4,format="%y/%m/%d")
> f<-data.frame(sam5,mkf)
> plot(f,type="l")
> # This works ok, but none of the labels appear on the x-axis, so I thought
I
> would convert them using
> # as.POSIXct:
>
> sam6<-format(as.POSIXct(sam5), "%b-%y")
> mon<-factor(as.character(sam6),levels=sam6)
> f2<-data.frame(mon,mkf)
> plot(f2,type="l")
>
> The problem is that plot(f2,type="l") no longer produces a line
plot...
>
> Any help with this would be gratefully appreciated.
>
> Best wishes,
> Sion
>
>
> --
> Si?n Roberts
>
> Department of Geography,
> Queen Mary, University of London,
> London,
> E1 4NS.
>
> Tel: +44 20 7882 5400
> http://www.geog.qmul.ac.uk/postgraduate/student/roberts.html
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>

On Mon, 17 Apr 2006, s.e.roberts at qmul.ac.uk wrote:

Please do follow the posting guide and at least tell us your version of R 
and give a working example (mkf is missing)
> Dear R-help,
> I am having problems with plotting converted dates in chronological as
Mar-03,
> May-03...Jul-04.
> My script is:
>
>
sam4<-c("03/03/01","03/05/01","03/07/01","03/09/01","03/11/01","04/01/01","04/03/01","04/05/01","04/07/01")
> sam5<-strptime(sam4,format="%y/%m/%d")
I would suggest you use as.Date here, for you have dates, not date-times.
> f<-data.frame(sam5,mkf)
> plot(f,type="l")
> # This works ok, but none of the labels appear on the x-axis,
It works for me: it is not intended to plot your labels (and plot.default 
does not do that either).  If you want add a special axis, use axis.Date 
to do so.
> so I thought I
> would convert them using
> # as.POSIXct:
You have converted them to a factor, which is not what you want.
> sam6<-format(as.POSIXct(sam5), "%b-%y")
> mon<-factor(as.character(sam6),levels=sam6)
> f2<-data.frame(mon,mkf)
> plot(f2,type="l")
>
> The problem is that plot(f2,type="l") no longer produces a line
plot...
Why don't you use plot(sam5, mkf, type="l")?  That works, and in
fact
your example works in R 2.3.0RC, but creating a data frame you don't need 
is counter-productive.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595