Vi tager udgangspunkt i samme data som før:

library(ggplot2,quietly = TRUE)
bmd <- dget("https://statepi.statnoter.dk/data/bmd2.robj")
head(bmd)
  sex age   bmd
2   1  54 0.991
4   2  73 0.822
5   1  56 1.173
6   2  61 0.930
7   2  56 0.824
8   1  65 0.842

Et enkelt box-plot laves som vist her (læs mere om boxplots på http://statnoter.dk/index.php?pageID=157)

ggplot(data = bmd) +
    geom_boxplot(aes(x = "", y = bmd))

Opdeling

Med box-plots er der flere muligheder for at opdele data. Man kan benytte samme strategi som med punkt-diagrammet:

ggplot(data = bmd) +
    geom_boxplot(aes(x = "", y = bmd, color = sex))

Men kan kan også benytte muligheden for at angive en x-værdi. Prøv først at køre følgende kommando, og se om du kan regne ud hvad den gør (måske hjælper det lidt at se på plottet længere nede):

cut(bmd$age, breaks = c(0, 40, 50, 200))
   [1] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200]
  [11] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
  [21] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
  [31] (40,50]  (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
  [41] (40,50]  (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
  [51] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200]
  [61] (40,50]  (40,50]  (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200]
  [71] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200]
  [81] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (40,50]  (50,200]
  [91] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200]
 [101] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (50,200]
 [111] (50,200] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200]
 [121] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [131] (50,200] (50,200] (40,50]  (40,50]  (40,50]  (40,50]  (40,50]  (50,200] (50,200] (50,200]
 [141] (40,50]  (40,50]  (40,50]  (50,200] (0,40]   (50,200] (40,50]  (50,200] (50,200] (50,200]
 [151] (40,50]  (0,40]   (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (40,50] 
 [161] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (0,40]   (50,200] (50,200] (40,50] 
 [171] (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [181] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (0,40]   (40,50] 
 [191] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [201] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [211] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [221] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200]
 [231] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [241] (50,200] (50,200] (40,50]  (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200] (50,200]
 [251] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (40,50]  (40,50] 
 [261] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [271] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [281] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [291] (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (0,40]  
 [301] (50,200] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50] 
 [311] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200]
 [321] (50,200] (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [331] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200]
 [341] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200]
 [351] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (0,40]   (50,200] (50,200] (50,200]
 [361] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200]
 [371] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50]  (50,200]
 [381] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [391] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200]
 [401] (50,200] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200]
 [411] (50,200] (0,40]   (50,200] (40,50]  (50,200] (0,40]   (50,200] (50,200] (40,50]  (50,200]
 [421] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50]  (40,50]  (40,50] 
 [431] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [441] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50]  (40,50]  (40,50]  (50,200]
 [451] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200]
 [461] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [471] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200]
 [481] (50,200] (50,200] (40,50]  (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200] (40,50] 
 [491] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [501] (40,50]  (50,200] (50,200] (50,200] (0,40]   (50,200] (40,50]  (50,200] (50,200] (50,200]
 [511] (50,200] (0,40]   (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200]
 [521] (40,50]  (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [531] (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [541] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200]
 [551] (0,40]   (50,200] (50,200] (0,40]   (50,200] (40,50]  (40,50]  (50,200] (50,200] (50,200]
 [561] (50,200] (40,50]  (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200]
 [571] (40,50]  (40,50]  (40,50]  (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200]
 [581] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [591] (50,200] (50,200] (50,200] (40,50]  (40,50]  (40,50]  (50,200] (40,50]  (40,50]  (50,200]
 [601] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50] 
 [611] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [621] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [631] (40,50]  (0,40]   (40,50]  (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50]  (0,40]  
 [641] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50] 
 [651] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50] 
 [661] (50,200] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200]
 [671] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50] 
 [681] (40,50]  (40,50]  (0,40]   (40,50]  (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [691] (50,200] (50,200] (0,40]   (50,200] (50,200] (50,200] (50,200] (40,50]  (0,40]   (50,200]
 [701] (40,50]  (40,50]  (40,50]  (40,50]  (50,200] (50,200] (0,40]   (50,200] (50,200] (50,200]
 [711] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200]
 [721] (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [731] (50,200] (50,200] (50,200] (0,40]   (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200]
 [741] (50,200] (50,200] (50,200] (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [751] (50,200] (40,50]  (40,50]  (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200] (50,200]
 [761] (40,50]  (40,50]  (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (40,50]  (50,200]
 [771] (40,50]  (50,200] (50,200] (50,200] (40,50]  (0,40]   (50,200] (40,50]  (50,200] (50,200]
 [781] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200]
 [791] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (50,200]
 [801] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (0,40]   (50,200]
 [811] (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [821] (50,200] (0,40]   (50,200] (40,50]  (50,200] (40,50]  (50,200] (40,50]  (40,50]  (50,200]
 [831] (40,50]  (50,200] (0,40]   (50,200] (40,50]  (50,200] (50,200] (40,50]  (40,50]  (40,50] 
 [841] (50,200] (50,200] (40,50]  (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200]
 [851] (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200] (0,40]   (50,200] (50,200] (50,200]
 [861] (40,50]  (40,50]  (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (40,50] 
 [871] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50] 
 [881] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (50,200] (50,200]
 [891] (0,40]   (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200]
 [901] (40,50]  (50,200] (40,50]  (50,200] (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200]
 [911] (40,50]  (40,50]  (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [921] (40,50]  (40,50]  (40,50]  (50,200] (40,50]  (50,200] (40,50]  (40,50]  (0,40]   (40,50] 
 [931] (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (40,50]  (50,200] (40,50]  (50,200]
 [941] (40,50]  (0,40]   (40,50]  (50,200] (40,50]  (40,50]  (40,50]  (50,200] (50,200] (40,50] 
 [951] (50,200] (50,200] (50,200] (50,200] (40,50]  (40,50]  (50,200] (0,40]   (50,200] (40,50] 
 [961] (50,200] (40,50]  (50,200] (50,200] (50,200] (50,200] (0,40]   (50,200] (0,40]   (50,200]
 [971] (50,200] (50,200] (40,50]  (40,50]  (50,200] (50,200] (50,200] (40,50]  (40,50]  (50,200]
 [981] (50,200] (50,200] (50,200] (50,200] (50,200] (40,50]  (50,200] (40,50]  (50,200] (0,40]  
 [991] (50,200] (0,40]   (0,40]   (50,200] (50,200] (50,200] (50,200] (50,200] (50,200] (50,200]
 [ reached 'max' / getOption("max.print") -- omitted 2127 entries ]
Levels: (0,40] (40,50] (50,200]

Nu man vi lave et plot med en inddeling i aldersgrupper (og køn):

ggplot(data = bmd) +
    geom_boxplot(aes(x = cut(age, breaks = c(0, 40, 50, 200)), y = bmd, color = sex)) +
    scale_x_discrete(name = "Aldersgruppe") #Og så må vi hellere sørge for en passende etikette på x-aksen (som nu er en diskret skala)