[R] Order axis by number of entries in lattice plot

[Luigi Marongiu]

Dear all,
I am plotting some values with lattice barchart: the y-axis is
automatically ordered alphabetically; is it possible to order the
entries by number, so that the 'larger' histograms would be at the top
of the plot?
This is a working example

```
library(lattice)
Family = c("Adenoviridae", "Baculoviridae",  "Herpesviridae",   "Mimiviridae",
"Myoviridae", "Pandoraviridae",  "Phycodnaviridae", "Podoviridae",
"Polydnaviridae",  "Retroviridae", "Siphoviridae",    "Unassigned")
Normal = c(7, 15, 24,  8, 65, 24, 17, 16,  8, 15, 49 , 9)
Tumour =c(  17,  75,  94,  14, 242,  28,  41,  69,  12,  11, 305,  51)
Metastasis =c(41,  66,  95,   3, 173,  22,  33, 101,  12,  12, 552,  57)
df = data.frame(Family, Normal, Tumour, Metastasis, stringsAsFactors = FALSE)
COLS = c("darkolivegreen3", "brown3", "darkorchid3")
barchart(Family ~ Normal+Tumour+Metastasis, data = df, stack = TRUE,
         xlim=c(1,1000),
         main = "Alphabetical order",
         xlab = expression(bold("Number of species")),
         ylab = expression(bold("Families")),
         auto.key = list(space = "top", columns=3),
         par.settings = list(superpose.polygon = list(col = COLS)))
```


-- 
Best regards,
Luigi