我们的unit(c(t, r, b, l), "cm")边距大小分别位于顶部、右侧、底部和左侧。实际上有一个默认值:
theme_get()$plot.margin
# [1] 5.5pt 5.5pt 5.5pt 5.5pt
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一个例子:
qplot(mpg, wt, data = mtcars) +
theme(plot.margin = unit(c(5, 15, 25, 35), "pt"),
plot.background = element_rect(fill = "grey90"))
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