如何确保ggplot中stat_cor元素的负号导出显示正常？

负号显示成方框本质是字体不兼容——ggplot生成的负号字符（可能是特殊的长破折号）在PPT默认字体里找不到对应字形，或者导出时没正确嵌入字体。给你几个实用的解决思路：

• 统一图表所有文本的字体为PPT兼容的常用字体
  直接在ggplot的theme里指定所有文本用Arial、微软雅黑这类PPT原生支持的字体，同时给stat_cor单独指定字体（它有时不会自动继承theme设置）：

  # 修改theme部分，添加family参数
  theme(plot.title = element_text(face = "bold", size = 20, family = "Arial"),
        legend.position = "none",
        axis.title = element_text(face="bold", size=24, family = "Arial"),
        axis.text = element_text(size=24, family = "Arial"),
        text = element_text(family = "Arial") # 统一全局文本字体
      ) +
  # 修改stat_cor，添加family参数
  stat_cor(label.y.npc="top", label.x.npc = "left",
           size=7,
           method="pearson",
           family = "Arial")
  

• 手动生成标注标签，替换特殊负号
  绕过stat_cor自动生成的标签，自己计算R值并构造带普通ASCII负号的标签，再用annotate添加到图表：

  # 手动计算皮尔逊相关系数
  cor_test <- cor.test(data$x_value, data$y_value, method = "pearson")
  r_val <- round(cor_test$estimate, 2)
  # 构造标签，确保用普通负号
  cor_label <- paste0("R = ", ifelse(r_val < 0, "-", ""), abs(r_val))
  
  # 把stat_cor替换成annotate
  p <- data %>%
    ggplot(aes_string(x = "x_value", y = "y_value")) + # 你的其他绘图代码
    geom_smooth(method = "lm", formula = y ~x, se=TRUE, color="black") + 
    geom_point(aes(shape=group, fill= group), size=4) +
    labs(title = "Title", y = "Y title", x= "X title" ) +
    scale_x_continuous(breaks=seq(0, 10, 1), limits=c(0, 10)) +
    scale_y_continuous(breaks=seq(0, 400, 25), limits=c(0, 400))+
    theme_bw() +
    theme(plot.title = element_text(face = "bold", size = 20),
          legend.position = "none",
          axis.title = element_text(face="bold", size=24),
          axis.text = element_text(size=24)
        ) +
    annotate("text", x = 1, y = 400, label = cor_label, size = 7, family = "Arial", hjust = 0)
  

• 调整dml导出参数，强制指定字体
  用officer包的dml()导出时，指定font_family参数，确保矢量图嵌入兼容字体：

  graphs <- ph_with(graphs, dml(ggobj = p, font_family = "Arial"), location = ph_location_fullsize())
  

内容的提问来源于stack exchange，提问作者gsm