创建带有副标题的 ggplotly 对象

Question

我正在绘制散点图，ggplot()如下所示：

library(data.table)
library(plotly)
library(ggplot2)
library(lubridate)

dt.allData <- data.table(date = seq(as.Date('2020-01-01'), by = '1 day', length.out = 365),
                         DE = rnorm(365, 4, 1), Austria = rnorm(365, 10, 2), 
                         Czechia = rnorm(365, 1, 2), check.names = FALSE)

## Calculate Pearson correlation coefficient: ##
corrCoeff <- cor(dt.allData$Austria, dt.allData$DE,  method = "pearson", use = "complete.obs")
corrCoeff <- round(corrCoeff, digits = 2)

## Linear regression function extraction by creating linear model: ##
regLine <- lm(DE ~ Austria, data = dt.allData)

## Extract k and d values for the linear function f(x) = kx+d: ##
k <- round(regLine$coef[2], digits = 5)
d <- round(regLine$coef[1], digits = 2)
linRegFunction <- paste0("y = ", d, " + (", k, ")x")

## PLOT: ##
p1 <- ggplot(data = dt.allData, aes(x = Austria, y = DE, 
                                    text = paste("Date: ", date, '\n',
                                                 "Austria: ", Austria, "MWh/h", '\n',
                                                 "DE: ", DE, "\u20ac/MWh"),
                                    group = 1)
      ) +
      geom_point(aes(color = ifelse(date >= now()-weeks(5), "#419F44", "#F07D00"))) +
      scale_color_manual(values = c("#F07D00", "#419F44")) +
      geom_smooth(method = "lm", se = FALSE, color = "#007d3c") +
      annotate("text", x = 10, y = 10,
               label = paste("\u03c1 =", corrCoeff, '\n',
                             linRegFunction), parse = TRUE) +
      theme_classic() +
      theme(legend.position = "none") +
      theme(panel.background = element_blank()) +
      xlab("Austria") +
      ylab("DE")+
      ggtitle("DE vs Austria") +
      theme(plot.title = element_text(hjust = 0.5, face = "bold"))

# Correlation plot converting from ggplot to plotly: #
plot <- plotly::ggplotly(p1, tooltip = "text")

这里给出了以下情节：

我用annotate()来表示相关系数和回归函数。我手动定义x和y坐标，以便文本输出显示在顶部中间。由于我有一些dt.allData具有不同轴缩放比例的此类数据表，因此我想在图中定义文本应始终显示在顶部中间，具体取决于轴缩放比例，而无需之前手动定义x和y协调。

Answer 1

我建议使用ggtitleand hjust = 0.5：

编辑：使用plotly::layout和span标签来创建标题：

library(data.table)
library(ggplot2)
library(plotly)
library(lubridate)

dt.allData <- data.table(date = seq(as.Date('2020-01-01'), by = '1 day', length.out = 365),
                         DE = rnorm(365, 4, 1), Austria = rnorm(365, 10, 2), 
                         Czechia = rnorm(365, 1, 2), check.names = FALSE)

## Calculate Pearson correlation coefficient: ##
corrCoeff <- cor(dt.allData$Austria, dt.allData$DE,  method = "pearson", use = "complete.obs")
corrCoeff <- round(corrCoeff, digits = 2)

## Linear regression function extraction by creating linear model: ##
regLine <- lm(DE ~ Austria, data = dt.allData)

## Extract k and d values for the linear function f(x) = kx+d: ##
k <- round(regLine$coef[2], digits = 5)
d <- round(regLine$coef[1], digits = 2)
linRegFunction <- paste0("y = ", d, " + (", k, ")x")

## PLOT: ##
p1 <- ggplot(data = dt.allData, aes(x = Austria, y = DE, 
                                    text = paste("Date: ", date, '\n',
                                                 "Austria: ", Austria, "MWh/h", '\n',
                                                 "DE: ", DE, "\u20ac/MWh"),
                                    group = 1)
) +
  geom_point(aes(color = ifelse(date >= now()-weeks(5), "#419F44", "#F07D00"))) +
  scale_color_manual(values = c("#F07D00", "#419F44")) +
  geom_smooth(method = "lm", formula = 'y ~ x', se = FALSE, color = "#007d3c") +
  # ggtitle(label = paste("My pretty useful title", '\n', "\u03c1 =", corrCoeff, '\n', linRegFunction)) +
  theme_classic() +
  theme(plot.title = element_text(hjust = 0.5)) +
  theme(legend.position = "none") +
  theme(panel.background = element_blank()) +
  xlab("Austria") +
  ylab("DE")

# Correlation plot converting from ggplot to plotly: #
# using span tag (directly in control of font-size):
span_plot <- plotly::ggplotly(p1, tooltip = "text") %>% layout(
    title = paste(
      '<b>My pretty useful title</b>',
      '<br><span style="font-size: 15px;">',
      '\u03c1 =<i>',
      corrCoeff,
      '</i><br>',
      linRegFunction,
      '</span>'
    ),
    margin = list(t = 100)
  )
span_plot

编辑：sup根据此答案添加替代方案

# using sup tag:
sup_plot <- plotly::ggplotly(p1, tooltip = "text") %>% layout(
    title = paste(
      '<b>My pretty useful title</b>',
      '<br><sup>',
      "\u03c1 =<i>",
      corrCoeff,
      '</i><br>',
      linRegFunction,
      '</sup>'
    ),
    margin = list(t = 100)
  )
sup_plot

在这里您可以在plotly 文档中找到一些相关信息。