1.展示名義變量和缺失值變量的關系
導入lattice包,
attach(algae)
> histogram(~mxPH|season,data = algae)
> algae$season <- factor(algae$season,levels = c("spring","summer","autumn","winter"))
![](https://img.laitimes.com/img/9ZDMuAjOiMmIsIjOiQnIsIiNwgDN1QTN5ADOxgDM1EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
繪制不同季節的mxPH的直方圖,由于直方圖相似,是以收集樣本時改年的季節對變量mxPH的值沒有顯著影響,可以用多個名義變量進行組合
histogram(~mxPH|size*speed,data = algae)