ggplot2如何在不同比例尺的轴上使散点图上的水平和垂直误差条大小相同

Question

我正在尝试制作x轴和y轴都有误差条的汇总散点图。我希望错误条哈希的大小相同。然而，因为我有不同比例的轴(例如，海胆丰度与珊瑚生长率)，我的错误条哈希值大小不同。

我使用了geom_errorbar()和geom_errorbarh()的"width“和"height”参数来手动更改宽度和高度。但是，因为我有很多图形，所以我想看看是否有一种方法可以将错误条形散列编码为相同的大小，这样我就可以在具有不同轴的其他图形上使用此代码。

数据库

urchin_vs_growth_summary_data <- structure(list(Site_long = c("Waikiki", "Waikiki", "Hanauma Bay", 
"Hanauma Bay"), Treatment_long = c("Closed", "Open", "Closed", 
"Open"), growth_mean = c(1.60941173649527, 1.40241172055135, 
0.977166214960325, 1.99458408579477), growth_sd = c(0.685274483494003, 
0.7123570094737, 0.303273008779028, 1.00414981259471), growth_lower = c(1.41159003273825, 
1.18762800080554, 0.853355527582455, 1.58464164143337), growth_upper = c(1.80723344025229, 
1.61719544029716, 1.1009769023382, 2.40452653015617), urchin_mean = c(0.166666666666667, 
0.375, 3.66666666666667, 22.75), urchin_sd = c(0.372677996249965, 
0.414578098794425, 2.73353657780945, 17.3066701977398), urchin_lower = c(0.0590837959386828, 
0.255321611530458, 2.87756262714768, 17.7539946512794), urchin_upper = c(0.27424953739465, 
0.494678388469542, 4.45577070618566, 27.7460053487206), Shelter = structure(c(1L, 
2L, 1L, 2L), .Label = c("Low", "High"), class = "factor")), row.names = c(NA, 
-4L), groups = structure(list(Site_long = c("Hanauma Bay", "Waikiki"
), .rows = list(3:4, 1:2)), row.names = c(NA, -2L), class = c("tbl_df", 
"tbl", "data.frame"), .drop = TRUE), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"))

海胆丰度与珊瑚生长数字代码

urchin_vs_growth_plot <- ggplot(data = urchin_vs_growth_summary_data, 
                                aes(x = urchin_mean, y = growth_mean, 
                                    fill = interaction(Site_long, Shelter), 
                                    shape = interaction(Site_long, Shelter))) + 
  geom_point(aes(size = 5)) +
  ggtitle("Urchin Abundance vs. Coral Growth") +
  scale_x_continuous(breaks = seq(0,24,3)) +
  scale_y_continuous(breaks = seq(0, 3, 0.5)) +
  scale_shape_manual(name = 'Site x Shelter', values = c(21, 24, 21, 24), 
                     labels = c("Hanauma Bay - Low", "Waikiki - Low", 
                                "Hanauma Bay - High", "Waikiki - High")) +
  scale_fill_manual(name = "Site x Shelter", values = c(NA, NA, 1, 1), 
                    labels = c("Hanauma Bay - Low", "Waikiki - Low", 
                               "Hanauma Bay - High", "Waikiki - High")) +
  geom_smooth(aes(group = 1), method ="lm", show.legend = FALSE) +
  guides(size = FALSE, linetype = FALSE, 
         shape = guide_legend(override.aes = list(size = 4.5)), 
         color = guide_legend(override.aes = list(fill = NA))) +
  theme(text = element_text(size = 15)) +
  geom_errorbar(aes(ymin = growth_lower, ymax = growth_upper), width = 0.5) + 
  geom_errorbarh(aes(xmin = urchin_lower, xmax = urchin_upper), height = 0.5) +
  labs(x = "Mean urchin abundance ± SEM", 
       y = expression(paste("Mean coral growth (cm"^"2","/quarter) ± 95% SEM"))) +
  theme_bw() + 
  theme(panel.border = element_blank(), 
        panel.grid.major = element_blank(), 
        panel.grid.minor = element_blank(), 
        axis.line = element_line(colour = "black"), 
        axis.title = element_text(size = rel(1.5)), 
        axis.title.y = element_text(size = rel(1)), 
        axis.text = element_text(size = rel(1.5)), 
        axis.text.y = element_text(angle = 90), 
        legend.text = element_text(size = rel(1)), 
        legend.title = element_text(size = rel(1), face = "bold"), 
        legend.position = "none", 
        plot.title = element_text(size = 20, hjust = 0.5, vjust = -1.5)) 

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我正在寻找创建通用代码，将允许我缩放错误条哈希在我的所有图形相同的大小(大多数，如果不是所有都有不同单位或比例的x和y轴)。感谢您的投入！

Answer 1

一种方法是创建图，提取x和y范围(如here所述)，并根据这些范围缩放错误条哈希值。这将产生与绘图的整体纵横比成比例的散列；只有当绘图本身是完全正方形时，水平和垂直散列才会完全相等。但是，如果您只是在寻找一种使散列看起来大致相似的方法，这可能已经足够好了。

创建绘图(没有错误条)：

urchin_vs_growth_plot <- ggplot(data = urchin_vs_growth_summary_data, 
                                aes(x = urchin_mean, y = growth_mean, 
                                    fill = interaction(Site_long, Shelter), 
                                    shape = interaction(Site_long, Shelter))) + 
  geom_point(size = 5) +
  ggtitle("Urchin Abundance vs. Coral Growth") +
  scale_x_continuous(breaks = seq(0,24,3)) +
  scale_y_continuous(breaks = seq(0, 3, 0.5)) +
  scale_shape_manual(name = 'Site x Shelter', values = c(21, 24, 21, 24), 
                     labels = c("Hanauma Bay - Low", "Waikiki - Low", 
                                "Hanauma Bay - High", "Waikiki - High")) +
  scale_fill_manual(name = "Site x Shelter", values = c(NA, NA, 1, 1), 
                    labels = c("Hanauma Bay - Low", "Waikiki - Low", 
                               "Hanauma Bay - High", "Waikiki - High")) +
  geom_smooth(aes(group = 1), method ="lm", show.legend = FALSE) +
  guides(size = FALSE, linetype = FALSE, 
         shape = guide_legend(override.aes = list(size = 4.5)), 
         color = guide_legend(override.aes = list(fill = NA))) +
  theme(text = element_text(size = 15)) +
  labs(x = "Mean urchin abundance ± SEM", 
       y = expression(paste("Mean coral growth (cm"^"2","/quarter) ± 95% SEM"))) +
  theme_bw() + 
  theme(panel.border = element_blank(), 
        panel.grid.major = element_blank(), 
        panel.grid.minor = element_blank(), 
        axis.line = element_line(colour = "black"), 
        axis.title = element_text(size = rel(1.5)), 
        axis.title.y = element_text(size = rel(1)), 
        axis.text = element_text(size = rel(1.5)), 
        axis.text.y = element_text(angle = 90), 
        legend.text = element_text(size = rel(1)), 
        legend.title = element_text(size = rel(1), face = "bold"), 
        legend.position = "none", 
        plot.title = element_text(size = 20, hjust = 0.5, vjust = -1.5))

将散列宽度设置为x和y轴大小的二十分之一(当然，可以根据需要调整实际值)：

hash.width.x = diff(layer_scales(urchin_vs_growth_plot)$x$range$range) / 20
hash.width.y = diff(layer_scales(urchin_vs_growth_plot)$y$range$range) / 20

添加错误条：

urchin_vs_growth_plot = urchin_vs_growth_plot +
  geom_errorbar(aes(ymin = growth_lower, ymax = growth_upper), width = hash.width.x) +
  geom_errorbarh(aes(xmin = urchin_lower, xmax = urchin_upper), height = hash.width.y)

结果是：

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要对许多绘图执行此操作，您可以创建一个小函数，该函数采用第一个绘图(没有错误条)，获取轴范围，并适当地添加错误条；然后将所有绘图包装在该函数中。