# [R] Adding text labels to lattice plots with multiple panels

Peter Ehlers ehlers at ucalgary.ca
Sat Apr 9 19:52:10 CEST 2011

```On 2011-04-09 06:21, Dennis Murphy wrote:
> Hi:
>
> One hopes that there is a more elegant solution than this bit of ad-hockery.
>> From your posted example:
>
> f1<- c(rep(c(rep("a", 3), rep("b", 3), rep("c", 3)), 2))
> f2<- c(rep("A", 9), rep("B", 9))
> dv<- c(0.9, 0.8, 0.85, 0.6, 0.65, 0.7, 0.8, 0.85, 0.8, 0.95, 0.85,
>   0.9, 0.65, 0.7, 0.75, 0.85, 0.9, 0.85)
> df<- data.frame(f1, f2, dv)
> df\$lab<- rep(1:6, each = 3)
>
> df\$lab2<- ''
> df\$lab2[seq(1, 16, by = 3)]<- 1:6        # adapt to your situation - seq(1,
> nrow(df) - 63, by = 64), perhaps
>
> bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
>   panel = function(x, y, ..., subscripts) {
>     lab<- df\$lab2[subscripts]
>     panel.bwplot(x, y,  ...)
>     panel.text(x, 0.55, labels = lab)
>   }
> )
>
> Alternatively, panel.text() takes an alpha = argument; for example,
>
> bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
>   panel = function(x, y, ..., subscripts) {
>     lab<- df\$lab[subscripts]
>     panel.bwplot(x, y,  ...)
>     panel.text(x, 0.55, labels = lab, alpha = 0.5)
>   }
> )
>
> You could toy with the value of alpha until something acceptable emerges.
> But as I said, there is probably a better solution and I'm happy to be
> educated if there is.

Here's a slight variation on your first solution which doesn't
require the data to be appropriately sorted, using your df:

bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
panel = function(x, y, ..., subscripts) {
lab <- df\$lab[subscripts]
lab[duplicated(lab)] <- ""
panel.bwplot(x, y,  ...)
panel.text(x, 0.55, labels = lab)
}
)

and another variation which sets the text positions to NA for
all but the first pass through the panel.text() function:

bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
panel = function(x, y, ..., subscripts) {
at.y <- rep(0.55, nrow(df))
is.na(at.y) <- which(duplicated(df\$lab))
panel.bwplot(x, y,  ...)
panel.text(x, at.y[subscripts], labels = df\$lab[subscripts])
}
)

I think that the alpha argument is too one-off, i.e. dependent on
how many levels in the boxplot.

Peter Ehlers

>
> HTH,
> Dennis
>
> On Sat, Apr 9, 2011 at 4:56 AM, Jeff Stevens<stev0175 at googlemail.com>wrote:
>
>> Hi,
>>
>> Thanks for the work around, Dennis.  My actual data set has 64
>> replicates for each factor level combination (rather than the 3 in the
>> example), so the overplotting is quite messy.  Any ideas on how to
>> avoid the overplotting?
>>
>> Jeff
>>
>>
>> On Fri, Apr 8, 2011 at 7:32 PM, Dennis Murphy<djmuser at gmail.com>  wrote:
>>> Hi:
>>>
>>> After a number of false starts, I finally consulted Deepayan's book and
>> the
>>> example on p. 73, suitably adapted, yielded a solution. Add a variable
>> for
>>> the labels and then...
>>>
>>> df\$lab<- rep(1:6, each = 3)
>>> bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
>>>   panel = function(x, y, ..., subscripts) {
>>>     lab<- df\$lab[subscripts]
>>>     panel.bwplot(x, y,  ...)
>>>     panel.text(x, 0.55, labels = lab)
>>>   }
>>> )
>>>
>>> If you look closely, you'll see that each label is overplotted three
>> times.
>>> A similar plot in ggplot2  would be
>>>
>>> library(ggplot2)
>>> ggplot(df, aes(x = f1, y = dv)) + geom_boxplot() +
>>>      geom_text(aes(x = as.numeric(f1), lab = lab), y = 0.55, alpha = 0.5)
>> +
>>>      facet_wrap( ~ f2) + ylim(0.5, 1)
>>>
>>> The alpha argument in geom_text() is designed to mitigate the
>> overplotting
>>> effect somewhat.
>>>
>>> HTH,
>>> Dennis
>>>
>>>
>>> On Fri, Apr 8, 2011 at 5:32 AM, Jeff Stevens<stev0175 at googlemail.com>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I am trying to add text to the bottom of a lattice bwplot with
>>>> multiple panels.  I would like to add a label below each boxplot, but
>>>> the labels do not come from the data.  I've tried the following, code:
>>>>
>>>> f1<- c(rep(c(rep("a", 3), rep("b", 3), rep("c", 3)), 2))
>>>> f2<- c(rep("A", 9), rep("B", 9))
>>>> dv<- c(0.9, 0.8, 0.85, 0.6, 0.65, 0.7, 0.8, 0.85, 0.8, 0.95, 0.85,
>>>> 0.9, 0.65, 0.7, 0.75, 0.85, 0.9, 0.85)
>>>> df<- data.frame(f1, f2, dv)
>>>> lab<- c(1, 2, 3, 4, 5, 6)
>>>>
>>>> bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
>>>>   panel = function(x, y, ...) {
>>>>     panel.bwplot(x, y, ...)
>>>>     panel.text(x, 0.55, labels = lab)
>>>>   }
>>>> )
>>>>
>>>> I have two problems.  First, the label values are writing over one
>>>> another.  I wrote a horrible hack (below) that fixes that problem, but
>>>> I would like to know if there are better/more flexible ways to do
>>>> this.
>>>>
>>>> bwplot(dv ~ f1 | f2, data = df, ylim = c(0.5, 1),
>>>>   panel = function(x, y, ...) {
>>>>     x2<- as.factor(c("a", "b", "c"))
>>>>     panel.bwplot(x, y, ...)
>>>>     panel.text(x2, 0.55, labels = lab)
>>>>   }
>>>> )
>>>>
>>>> Second, when using the horrible hack the first values are repeated in
>>>> the second panel.  How do I display the correct values in the second
>>>> panel?  The subscripts argument seems to do the trick when the labels
>>>> come from the data, but how do I get the proper values when the labels
>>>> come from outside of the data?
>>>>
>>>>
>>>> Many thanks,
>>>> Jeff
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>
>>
>>
>> --
>> Jeff Stevens
>> Center for Adaptive Behavior and Cognition
>> Max Planck Institute for Human Development
>> Lentzealle 94
>> 14195 Berlin, Germany
>>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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