r - 如何从 R 绘图图中获取坐标

Question

我一直在拼命地解决一个看似基本的问题。
想象一下，您有一个散点图，例如…… 10 个标记。
我想这个图是在 Shiny 环境中使用 plotly 生成的。

可以使用 event_data("plotly_click") 轻松获得这些标记的坐标。代码。

现在假设您不需要这些标记的坐标，而是通过鼠标单击生成的坐标，但恰好在不存在标记的地方(例如，因为您想在那里设置一个新标记，并且您想重新使用来自鼠标点击的信息)。

我无法使用 onclick() 获得这样的行为， 管他呢。

任何的想法 ？

Answer 1

您可以在 plotly 中添加 D3 事件监听器

Plotly.d3.select('.plotly').on('click', function(d, i) {})

进而

根据点击位置检索相对的 x 和 y 值( d3.event.layerX 和 layerY )

调整相对图形位置 ( document.getElementsByClassName('bg')[0].attributes['x'] )

最后根据轴范围 ( myPlot.layout.xaxis.range[0] )

计算新值

新款 x和 y然后将值推送到现有图形

Plotly.extendTraces(myPlot, {
      x: [[x]],
      y: [[y]]
    }, [1]);

完整的R代码

library("plotly")
library("htmlwidgets")

p <- plot_ly(x = c( -2, 0, 2 ),y = c( -2, 1, 2), type = 'scatter' ,mode = 'lines+markers') %>% 
  add_trace(x=c(-1,0.4,2),y=c(2, 0, -1),type='scatter',mode='lines+markers') %>% 
  layout(hovermode='closest')
javascript <- "
var myPlot = document.getElementsByClassName('plotly')[0];
Number.prototype.between = function (min, max) {
  return this >= min && this <= max;
};

Plotly.d3.select('.plotly').on('click', function(d, i) {
  var e = Plotly.d3.event;
  var bg = document.getElementsByClassName('bg')[0];
  var x = ((e.layerX - bg.attributes['x'].value + 4) / (bg.attributes['width'].value)) * (myPlot.layout.xaxis.range[1] - myPlot.layout.xaxis.range[0]) + myPlot.layout.xaxis.range[0];
    var y =((e.layerY - bg.attributes['y'].value + 4) / (bg.attributes['height'].value)) * (myPlot.layout.yaxis.range[0] - myPlot.layout.yaxis.range[1]) + myPlot.layout.yaxis.range[1]
  if (x.between(myPlot.layout.xaxis.range[0], myPlot.layout.xaxis.range[1]) && 
y.between(myPlot.layout.yaxis.range[0], myPlot.layout.yaxis.range[1])) {
    Plotly.extendTraces(myPlot, {
      x: [[x]],
      y: [[y]]
    }, [1]);
  }
});"
p <- htmlwidgets::prependContent(p, onStaticRenderComplete(javascript), data=list(''))
p

交互式 Javascript 示例

var traces = [{
  x: [1, 2, 3, 4],
  y: [10, 15, 13, 17],
  mode: 'markers',
  type: 'scatter'
}];

traces.push({
  x: [2, 3, 4, 5],
  y: [16, 5, 11, 9],
  mode: 'markers',
  type: 'scatter'
});

traces.push({
  x: [1, 2, 3, 4],
  y: [12, 9, 15, 12],
  mode: 'markers',
  type: 'scatter'
});

traces.push({
  x: [],
  y: [],
  mode: 'lines+markers',
  type: 'scatter'
});

var myPlot = document.getElementById('myPlot')
Plotly.newPlot('myPlot', traces, {hovermode: 'closest'});

Number.prototype.between = function(min, max) {
  return this >= min && this <= max;
};

Plotly.d3.select(".plotly").on('click', function(d, i) {
  var e = Plotly.d3.event;
  var bg = document.getElementsByClassName('bg')[0];
  var x = ((e.layerX - bg.attributes['x'].value + 4) / (bg.attributes['width'].value)) * (myPlot.layout.xaxis.range[1] - myPlot.layout.xaxis.range[0]) + myPlot.layout.xaxis.range[0];
  var y = ((e.layerY - bg.attributes['y'].value + 4) / (bg.attributes['height'].value)) * (myPlot.layout.yaxis.range[0] - myPlot.layout.yaxis.range[1]) + myPlot.layout.yaxis.range[1]
  if (x.between(myPlot.layout.xaxis.range[0], myPlot.layout.xaxis.range[1]) &&
    y.between(myPlot.layout.yaxis.range[0], myPlot.layout.yaxis.range[1])) {
    Plotly.extendTraces(myPlot, {
      x: [
        [x]
      ],
      y: [
        [y]
      ]
    }, [3]);
  }
});

<script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
<div id="myPlot" style="width:100%;height:100%"></div>

Shiny 的例子

library(shiny)
library("plotly")
library("htmlwidgets")

ui <- fluidPage(
  plotlyOutput("plot")
)

server <- function(input, output) {
   javascript <- "
function(el, x){
  Number.prototype.between = function (min, max) {
   return this >= min && this <= max;
  };

  Plotly.d3.select('.plotly').on('click', function(d, i) {
  var e = Plotly.d3.event;
  var bg = document.getElementsByClassName('bg')[0];
  var x = ((e.layerX - bg.attributes['x'].value + 4) / (bg.attributes['width'].value)) * (el.layout.xaxis.range[1] - el.layout.xaxis.range[0]) + el.layout.xaxis.range[0];
  var y =((e.layerY - bg.attributes['y'].value + 4) / (bg.attributes['height'].value)) * (el.layout.yaxis.range[0] - el.layout.yaxis.range[1]) + el.layout.yaxis.range[1]
  if (x.between(el.layout.xaxis.range[0], el.layout.xaxis.range[1]) && y.between(el.layout.yaxis.range[0], el.layout.yaxis.range[1])) {
    Plotly.extendTraces(el, {
     x: [[x]],
     y: [[y]]
    }, [1]);
  }
});
}"
  output$plot <- renderPlotly({
    plot_ly(x = c( -2, 0, 2 ),y = c( -2, 1, 2), type = 'scatter' ,mode = 'lines+markers') %>% 
    add_trace(x=c(-1,0.4,2),y=c(2, 0, -1),type='scatter',mode='lines+markers') %>% 
    layout(hovermode='closest') %>% onRender(javascript)
  })
}

shinyApp(ui = ui, server = server)