On 5/8/08, Ola Caster <ola.caster at gmail.com>
wrote:> Dear help list,
>
> Is it possible to draw lattice histograms (i.e. use the histogram()
function
> and not the hist() function) with objects of class "Date"?
Sort of. The default calculation of 'breaks' doesn't work, so
histogram(~date, data=my.data)
will currently fail (I will fix this in the next update). However,
histogram(~date, data=my.data, breaks = 10)
histogram(~date, data=my.data, breaks = "fd")
etc., should work. The help page for histogram is somewhat ambiguous; it says:
breaks:
[...]
Other valid values
of 'breaks' are those of the 'breaks' argument in
'hist'.
This allows specification of 'breaks' as an integer giving
the number of bins (similar to 'nint'), as a character string
denoting a method, and as a function.
What is meant here is that valid values of breaks in 'hist.default'
will work, not those for any other methods. In particular, breaks
"months" will not work.
-Deepayan
> I've tried solutions like
>
> histogram(~date, data=my.data, breaks="months")
>
> but it doesn't seem to work.
>
> Any suggestions are welcome.
>
> Many thanks
> Ola Caster