[R] [FORGED] date format in xyplot

[Rolf Turner]

See inline below.

On 18/08/15 16:15, Christine Lee via R-help wrote:
> To whom it may concern,
>
> I have tried to plot some numbers against time with the time on the X-axis
> shown as "Jan", "Feb", etc.
>
> I used the following commands:
> Raw<-structure(list(Date = structure(c(6L, 7L, 2L, 4L, 12L, 9L, 7L,
> 2L, 4L, 12L), .Label = c("1/10", "1/11", "11/11", "12/11", "13/10",
> "19/9", "2/10", "2/11", "20/9", "26/11", "29/10", "29/11", "30/11",
> "31/10", "4/10", "6/10"), class = "factor"), Year = c(2002L,
> 2002L, 2002L, 2002L, 2002L, 2002L, 2002L, 2002L, 2002L, 2002L
> ), Station = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L,
> 2L), .Label = c("E", "F", "H", "I"), class = "factor"), Abun = c(3.42,
> 1.33, 3.67, 3.67, 3.92, 2.17, 2.5, 1.67, 6.33, 0.67), Date1 = structure(c(16697,
> 16710, 16740, 16751, 16768, 16698, 16710, 16740, 16751, 16768
> ), class = "Date")), .Names = c("Date", "Year", "Station", "Abun",
> "Date1"), row.names = c(NA, 10L), class = "data.frame")
>
> Raw$Date1<-as.Date(Raw$Date,"%d/%m")

What does this accomplish?  As far as I can tell Raw$Date1 is the same 
after doing this replacement as it was before.

> xyplot(Abun~Date1|as.factor(Year),Raw,type="p",xlab=list("Month",cex=1.5),
> lab=list("Abundance",cex=1.5),cex=2,pch=c(16,16,21),col=c("Black","Grey","Black"),
> strip=strip.custom(bg='white'),format="%B-%d")
>
> The date format shown on X-axis was just "10-1", "10-15"

Not what I get.

> I should be grateful if any one could help indicating what has gone wrong?

No idea.  When I try your code, the x-axis labels that I get are
"Oct 01", "Oct 15", ..., "Dec 01", which looks pretty much as it should.

General advice --- when you are getting unexpected results, try the 
example in a stripped down "keep it simple" form --- i.e. eliminate most 
of the bells and whistles in your very complicated call to xyplot(). 
That might give you a better chance at discerning what is causing things 
to go wrong for you.

cheers,

Rolf Turner

-- 
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276