服务器环境下如何导出R语言Plotly绘图？

在R语言中使用Plotly生成散点图，本地环境下执行以下代码可正常导出plot.html文件，但服务器环境中生成的文件为空，尝试saveWidget、orca工具均无法正常工作，寻求替代的HTML格式导出方法（优先）或PNG格式导出方法。

本地可正常运行的代码：

plot <- plot_ly(data = df, x = ~Vol1, y = ~Vol2, type = "scatter", mode = "markers", width = 900, height = 900,
       marker = list(symbol = "cross",size = 4, opacity = 0.5, color = "rgba(50,50,50,0.5)",alpha = I(0.8)))

save_html(plot, file = "plot.html")

一、HTML格式导出替代方案 #

1. 显式指定依赖路径或生成自包含文件 #

服务器环境常存在资源加载路径问题，可通过htmltools::save_html显式配置：

library(htmltools)
library(plotly)

plot <- plot_ly(data = df, x = ~Vol1, y = ~Vol2, type = "scatter", mode = "markers", width = 900, height = 900,
       marker = list(symbol = "cross",size = 4, opacity = 0.5, color = "rgba(50,50,50,0.5)",alpha = I(0.8)))

# 方式1：生成独立依赖文件夹（需服务器当前目录有写权限）
save_html(
  tagList(plot),
  file = "plot.html",
  libdir = "plotly_deps"
)

# 方式2：强制将所有依赖嵌入HTML文件（无需额外依赖文件夹）
save_html(
  tagList(plot),
  file = "plot.html",
  selfcontained = TRUE
)

2. 直接生成HTML字符串写入文件 #

绕过工具的依赖加载逻辑，手动生成完整HTML内容：

library(plotly)

plot <- plot_ly(data = df, x = ~Vol1, y = ~Vol2, type = "scatter", mode = "markers", width = 900, height = 900,
       marker = list(symbol = "cross",size = 4, opacity = 0.5, color = "rgba(50,50,50,0.5)",alpha = I(0.8)))

# 转换为HTML字符串
plot_html_str <- as.character(plotly::to_html(plot))

# 写入文件
writeLines(plot_html_str, "plot.html")

二、PNG格式导出替代方案 #

1. 使用webshot2截图导出 #

若服务器可安装webshot2（依赖Chrome/Chromium），可先临时保存HTML再截图：

library(plotly)
library(webshot2)

plot <- plot_ly(data = df, x = ~Vol1, y = ~Vol2, type = "scatter", mode = "markers", width = 900, height = 900,
       marker = list(symbol = "cross",size = 4, opacity = 0.5, color = "rgba(50,50,50,0.5)",alpha = I(0.8)))

# 临时保存HTML
save_html(plot, "temp_plot.html")

# 截图生成PNG
webshot("temp_plot.html", "plot.png", vwidth = 900, vheight = 900)

# 可选：删除临时文件
file.remove("temp_plot.html")

2. 转用ggplot2导出静态图 #

若无需交互性，可先转为ggplot2对象再导出PNG：

library(ggplot2)
library(plotly)

# 创建ggplot静态图
gg_plot <- ggplot(df, aes(x = Vol1, y = Vol2)) +
  geom_point(shape = "cross", size = 4, alpha = 0.5, color = "#323232") +
  theme_minimal()

# 导出PNG（按原尺寸换算，72为默认dpi）
ggsave("plot.png", gg_plot, width = 900/72, height = 900/72, dpi = 72)

# 若仍需交互版，可再转为plotly对象后用上述HTML方法导出
plot <- ggplotly(gg_plot)

内容的提问来源于stack exchange，提问作者Patriche Perin