spurious warning when mapping marker size

The simple scatterplot has a third variable mapped to the marker/point size. The plot looks perfect to me, but it throws a warning about multiple values. Each x & y value has exactly one size value.

Other than suppressing the warning, can a respecify this graph so it does not throw the warning?

Warning message:
`line.width` does not currently support multiple values.

Code:

plotly::plot_ly(
  data  = iris, 
  x     = ~Sepal.Length, 
  y     = ~Petal.Length, 
  size  = ~Sepal.Width,
  type  = 'scatter', 
  mode  = 'markers'
)

Graph:

Originally posted at https://stackoverflow.com/questions/52692760/spurious-warning-when-mapping-marker-size-in-plotly-r.

使用提供的 plotly::plot_ly() 散点图以及 iris 和 Sepal.Width 大小映射重现该警告。跟踪散点标记大小的处理过程以及报告的 line.width 警告。完成标准是绘图保留映射的标记大小，且不发出无关的多值警告。