R help - Mar 2011 - lattice xscale.components: different ticks on top/bottom axis

Good afternoon,

I am trying to create a plot where the bottom and top axes have the same
scale but different tick marks.  I tried user-defined xscale.component
function but it does not produce desired results.  Can anybody suggest
where my use of xscale.component function is incorrect?

For example, the code below tries to create a plot where horizontal axes
limits are c(0,10), top axis has ticks at odd integers, and bottom axis
has ticks at even integers.

library(lattice)

df <- data.frame(x=1:10,y=1:10)

xscale.components.A <- function(...,user.value=NULL) {
  # get default axes definition list; print user.value
  ans <- xscale.components.default(...)
  print(user.value)

  # start with the same definition of bottom and top axes
  ans$top <- ans$bottom
  
  # - bottom labels
  ans$bottom$labels$at <- seq(0,10,by=2)
  ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")

  # - top labels
  ans$top$labels$at <- seq(1,9,by=2)
  ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")

  # return axes definition list
  return(ans)
}

oltc <- xyplot(y~x,data=df,
 
scales=list(x=list(limits=c(0,10),at=0:10,alternating=3)),
               xscale.components=xscale.components.A,
               user.value=1)
print(oltc)

The code generates a figure with incorrectly placed bottom and top
labels.  Bottom labels "B-0", "B-2", ... are at 0, 1, ...
and top labels
"T-1", "T-3", ... are at 0, 1, ...  When axis-function runs
out of
labels, it replaces labels with NA.

It appears that lattice uses top$ticks$at to place labels and
top$labels$labels for labels.  Is there a way to override this behaviour
(other than to expand the "labels$labels" vector to be as long as
"ticks$at" vector and set necessary elements to "")?

Also, can user-parameter be passed into xscale.components() function?
(For example, locations and labels of ticks on the top axis).  In the
code above, print(user.value) returns NULL even though in the xyplot()
call user.value is 1.

Sincerely,
Boris Vasiliev.

On Fri, Mar 11, 2011 at 12:28 AM,  <Boris.Vasiliev at forces.gc.ca>
wrote:
> Good afternoon,
>
> I am trying to create a plot where the bottom and top axes have the same
> scale but different tick marks. ?I tried user-defined xscale.component
> function but it does not produce desired results. ?Can anybody suggest
> where my use of xscale.component function is incorrect?
>
> For example, the code below tries to create a plot where horizontal axes
> limits are c(0,10), top axis has ticks at odd integers, and bottom axis
> has ticks at even integers.
>
> library(lattice)
>
> df <- data.frame(x=1:10,y=1:10)
>
> xscale.components.A <- function(...,user.value=NULL) {
> ?# get default axes definition list; print user.value
> ?ans <- xscale.components.default(...)
> ?print(user.value)
>
> ?# start with the same definition of bottom and top axes
> ?ans$top <- ans$bottom
>
> ?# - bottom labels
> ?ans$bottom$labels$at <- seq(0,10,by=2)
> ?ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")
>
> ?# - top labels
> ?ans$top$labels$at <- seq(1,9,by=2)
> ?ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")
>
> ?# return axes definition list
> ?return(ans)
> }
>
> oltc <- xyplot(y~x,data=df,
>
> scales=list(x=list(limits=c(0,10),at=0:10,alternating=3)),
> ? ? ? ? ? ? ? xscale.components=xscale.components.A,
> ? ? ? ? ? ? ? user.value=1)
> print(oltc)
>
> The code generates a figure with incorrectly placed bottom and top
> labels. ?Bottom labels "B-0", "B-2", ... are at 0, 1,
... and top labels
> "T-1", "T-3", ... are at 0, 1, ... ?When axis-function
runs out of
> labels, it replaces labels with NA.
>
> It appears that lattice uses top$ticks$at to place labels and
> top$labels$labels for labels. ?Is there a way to override this behaviour
> (other than to expand the "labels$labels" vector to be as long as
> "ticks$at" vector and set necessary elements to "")?
Well, <top|bottom>$ticks$at is used to place the ticks, and $labels$at
is used to place the labels. They should typically be the same, but
you have changed one and not the other. Everything seems to work if
you set $ticks$at to the same values as $labels$at:


    ##  - bottom labels
+   ans$bottom$ticks$at <- seq(0,10,by=2)
    ans$bottom$labels$at <- seq(0,10,by=2)
    ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")

    ##  - top labels
+   ans$top$ticks$at <- seq(1,9,by=2)
    ans$top$labels$at <- seq(1,9,by=2)
    ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")

> Also, can user-parameter be passed into xscale.components() function?
> (For example, locations and labels of ticks on the top axis). ?In the
> code above, print(user.value) returns NULL even though in the xyplot()
> call user.value is 1.
No. Unrecognized arguments are passed to the panel function only, not
to any other function. However, you can always define an inline
function:

oltc <- xyplot(y~x,data=df,
               scales=list(x=list(limits=c(0,10), at = 0:10, alternating=3)),
               xscale.components = function(...)
xscale.components.A(..., user.value=1))

Hope that helps (and sorry for the late reply).

-Deepayan

> On Fri, Mar 11, 2011 at 12:28 AM,  
> <Boris.Vasiliev at forces.gc.ca> wrote:
> > Good afternoon,
> >
> > I am trying to create a plot where the bottom and top axes have the 
> > same scale but different tick marks. ?I tried user-defined 
> > xscale.component function but it does not produce desired results. ?
> > Can anybody suggest where my use of xscale.component 
> > function is incorrect?
> >
> > For example, the code below tries to create a plot where horizontal 
> > axes limits are c(0,10), top axis has ticks at odd integers, and 
> > bottom axis has ticks at even integers.
> >
> > library(lattice)
> >
> > df <- data.frame(x=1:10,y=1:10)
> >
> > xscale.components.A <- function(...,user.value=NULL) {
> > ?# get default axes definition list; print user.value
> > ?ans <- xscale.components.default(...)
> > ?print(user.value)
> >
> > ?# start with the same definition of bottom and top axes
> > ?ans$top <- ans$bottom
> >
> > ?# - bottom labels
> > ?ans$bottom$labels$at <- seq(0,10,by=2)
> > ?ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")
> >
> > ?# - top labels
> > ?ans$top$labels$at <- seq(1,9,by=2)
> > ?ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")
> >
> > ?# return axes definition list
> > ?return(ans)
> > }
> >
> > oltc <- xyplot(y~x,data=df,
> >
> > scales=list(x=list(limits=c(0,10),at=0:10,alternating=3)),
> > ? ? ? ? ? ? ? xscale.components=xscale.components.A,
> > ? ? ? ? ? ? ? user.value=1)
> > print(oltc)
> >
> > The code generates a figure with incorrectly placed bottom and top 
> > labels. ?Bottom labels "B-0", "B-2", ... are at 0,
1, ... and top
> > labels "T-1", "T-3", ... are at 0, 1, ... ?When
axis-function runs out
> > of labels, it replaces labels with NA.
> >
> > It appears that lattice uses top$ticks$at to place labels and 
> > top$labels$labels for labels. ?Is there a way to override this 
> > behaviour (other than to expand the "labels$labels" vector
to be as
> > long as "ticks$at" vector and set necessary elements to
"")?
> 
> Well, <top|bottom>$ticks$at is used to place the ticks, and 
> $labels$at is used to place the labels. They should typically 
> be the same, but you have changed one and not the other. 
> Everything seems to work if you set $ticks$at to the same 
> values as $labels$at:
> 
> 
>     ##  - bottom labels
> +   ans$bottom$ticks$at <- seq(0,10,by=2)
>     ans$bottom$labels$at <- seq(0,10,by=2)
>     ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")
> 
>     ##  - top labels
> +   ans$top$ticks$at <- seq(1,9,by=2)
>     ans$top$labels$at <- seq(1,9,by=2)
>     ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")
> 
> 
> > Also, can user-parameter be passed into xscale.components() 
> > function? (For example, locations and labels of ticks on the top 
> > axis). ?In the  code above, print(user.value) returns NULL even 
> > though in the xyplot() call user.value is 1.
> 
> No. Unrecognized arguments are passed to the panel function 
> only, not to any other function. However, you can always 
> define an inline
> function:
> 
> oltc <- xyplot(y~x,data=df,
>                scales=list(x=list(limits=c(0,10), at = 0:10, 
>                            alternating=3)),
>                xscale.components = function(...) 
>                            xscale.components.A(..., user.value=1))
> 
> Hope that helps (and sorry for the late reply).
> 
> -Deepayan
> 
Deepyan,

Thank you very much for your reply.  It makes things a bit clearer.  

It other words in the list prepared by xscale.components(), vectors
<top|bottom>$ticks$at and <top|bottom>$labels$at must be the same. 
If only every second tick is to be labelled then every second label should be
set explicitly to empty strings:

  ans$bottom$ticks$at <- seq(0,10,by=1)
  ans$bottom$labels$at <- seq(0,10,by=1)
  ans$bottom$labels$labels <-
paste("B",seq(0,10,by=1),sep="-")
  # replace  "B-1", "B-3", ... with ""
  ans$bottom$labels$labels[seq(2,11,by=2)] <- ""

Sincerely,
Boris.

On Sat, Apr 2, 2011 at 1:29 AM,  <Boris.Vasiliev at forces.gc.ca>
wrote:
>
>> On Fri, Mar 11, 2011 at 12:28 AM,
>> <Boris.Vasiliev at forces.gc.ca> wrote:
>> > Good afternoon,
>> >
>> > I am trying to create a plot where the bottom and top axes have
the
>> > same scale but different tick marks. ?I tried user-defined
>> > xscale.component function but it does not produce desired results.
>> > Can anybody suggest where my use of xscale.component
>> > function is incorrect?
>> >
>> > For example, the code below tries to create a plot where
horizontal
>> > axes limits are c(0,10), top axis has ticks at odd integers, and
>> > bottom axis has ticks at even integers.
>> >
>> > library(lattice)
>> >
>> > df <- data.frame(x=1:10,y=1:10)
>> >
>> > xscale.components.A <- function(...,user.value=NULL) {
>> > ?# get default axes definition list; print user.value
>> > ?ans <- xscale.components.default(...)
>> > ?print(user.value)
>> >
>> > ?# start with the same definition of bottom and top axes
>> > ?ans$top <- ans$bottom
>> >
>> > ?# - bottom labels
>> > ?ans$bottom$labels$at <- seq(0,10,by=2)
>> > ?ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")
>> >
>> > ?# - top labels
>> > ?ans$top$labels$at <- seq(1,9,by=2)
>> > ?ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")
>> >
>> > ?# return axes definition list
>> > ?return(ans)
>> > }
>> >
>> > oltc <- xyplot(y~x,data=df,
>> >
>> > scales=list(x=list(limits=c(0,10),at=0:10,alternating=3)),
>> > ? ? ? ? ? ? ? xscale.components=xscale.components.A,
>> > ? ? ? ? ? ? ? user.value=1)
>> > print(oltc)
>> >
>> > The code generates a figure with incorrectly placed bottom and top
>> > labels. ?Bottom labels "B-0", "B-2", ... are
at 0, 1, ... and top
>> > labels "T-1", "T-3", ... are at 0, 1, ...
?When axis-function runs out
>> > of labels, it replaces labels with NA.
>> >
>> > It appears that lattice uses top$ticks$at to place labels and
>> > top$labels$labels for labels. ?Is there a way to override this
>> > behaviour (other than to expand the "labels$labels"
vector to be as
>> > long as "ticks$at" vector and set necessary elements to
"")?
>>
>> Well, <top|bottom>$ticks$at is used to place the ticks, and
>> $labels$at is used to place the labels. They should typically
>> be the same, but you have changed one and not the other.
>> Everything seems to work if you set $ticks$at to the same
>> values as $labels$at:
>>
>>
>> ? ? ## ?- bottom labels
>> + ? ans$bottom$ticks$at <- seq(0,10,by=2)
>> ? ? ans$bottom$labels$at <- seq(0,10,by=2)
>> ? ? ans$bottom$labels$labels <-
paste("B",seq(0,10,by=2),sep="-")
>>
>> ? ? ## ?- top labels
>> + ? ans$top$ticks$at <- seq(1,9,by=2)
>> ? ? ans$top$labels$at <- seq(1,9,by=2)
>> ? ? ans$top$labels$labels <-
paste("T",seq(1,9,by=2),sep="-")
>>
>>
>> > Also, can user-parameter be passed into xscale.components()
>> > function? (For example, locations and labels of ticks on the top
>> > axis). ?In the ?code above, print(user.value) returns NULL even
>> > though in the xyplot() call user.value is 1.
>>
>> No. Unrecognized arguments are passed to the panel function
>> only, not to any other function. However, you can always
>> define an inline
>> function:
>>
>> oltc <- xyplot(y~x,data=df,
>> ? ? ? ? ? ? ? ?scales=list(x=list(limits=c(0,10), at = 0:10,
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ?alternating=3)),
>> ? ? ? ? ? ? ? ?xscale.components = function(...)
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ?xscale.components.A(..., user.value=1))
>>
>> Hope that helps (and sorry for the late reply).
>>
>> -Deepayan
>>
>
> Deepyan,
>
> Thank you very much for your reply. ?It makes things a bit clearer.
>
> It other words in the list prepared by xscale.components(), vectors
> <top|bottom>$ticks$at and <top|bottom>$labels$at must be the
same.
> If only every second tick is to be labelled then every second label
> should be set explicitly to empty strings:
Now when you put it that way, the current behaviour does seem wrong (I
didn't read your original post carefully enough). I guess this was one
of the not-yet-implemented things mentioned in the Details section of
?xscale.components.default.

I have added support for different ticks$at and labels$at in the SVN
sources in r-forge. You can test it from there (your original code
works as expected). I won't make a new release on CRAN until after R
2.13 is released (we are almost in code freeze now).

-Deepayan