带函数的ggplot中的Facet-wrap

Question

@Allan Cameron帮助我编写了一段代码，当我绘制两个变量时，它会自动将R2和p值(来自LM)放在图形的左上角。

然而，我不能让它与facet_wrap一起工作。例如，在mtcar数据集中，如果我想要对disp绘制wt，我可以这样做，但如果我想要使用facet_wrap为每个柱面组(例如4、6、8)绘制一幅图，则会收到以下错误消息

At least one layer must contain all faceting variables: `cyl`.
* Plot is missing `cyl`
* Layer 1 is missing `cyl`
* Layer 2 is missing `cyl`
* Layer 3 is missing `cyl`
* Layer 4 is missing `cyl`

以下是代码

ggplotRegression <- function (fit, title) {
  
  require(ggplot2)
  lab <- grid::textGrob(label = paste0(
    as.character(as.expression(fit$call$formula)), "\n",
    "Adj R\u00b2 = ",
    signif(summary(fit)$adj.r.squared, 1),
    ",  p = ", signif(summary(fit)$coef[2,4], 1)),
     x = unit(0.05, "npc"), 
     y = unit(0.9, "npc"), just = "left",
     gp = grid::gpar(size = 14, fontface = "bold"))
  ggplot(fit$model, aes_string(x = names(fit$model)[2], 
                               y = names(fit$model)[1])) + 
    ggtitle(title) +
    geom_point() +
    stat_smooth(method = "lm", col = "red") +
    annotation_custom(lab)
}


ggplotRegression(lm(disp ~ wt, data = mtcars), "My Title") +
  geom_point(size = 3.74, colour = "#0c4c8a") +
  theme_bw()+
  facet_wrap(vars(cyl), scales = "free")

另外，我也不太明白代码是做什么的？

Answer 1

您会遇到错误，因为该函数依赖于fit$model，如果您将lm(disp ~ wt, data = mtcars)输入到数据中，您可以看到cyl不再位于ggplot对象中：

fit = lm(disp ~ wt, data = mtcars)
head(fit$model)

                  disp    wt
Mazda RX4          160 2.620
Mazda RX4 Wag      160 2.875
Datsun 710         108 2.320
Hornet 4 Drive     258 3.215
Hornet Sportabout  360 3.440
Valiant            225 3.460

@Allan为您提供的基本上是编辑1个绘图并在文本中插入。如果你想在不同的数据子集上拟合三个线性模型，应该是这样的：

library(ggpmisc)
library(ggplot2)

formula = y~x

ggplot(mtcars, aes(wt, disp)) +
geom_point() +
geom_smooth(method = "lm",formula=formula) +
facet_wrap(~cyl, scales = "free")+
stat_poly_eq(
aes(label = paste(stat(adj.rr.label), stat(p.value.label),sep = "*\", \"*")),
formula = formula, parse = TRUE,size=3)

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