Set marker size in plotly
<p>How can I change the marker size in plotly in R on a map? If I set the <code>size</code> argument to any number it makes it the same, too big size. And if I map it to a variable in my data, the markers are to small to really be able to tell the difference in the first place. Ideally I would like to increase the base size and keep the proportional aspect through mapping to the variable.</p>

<p>Reproducible example:</p>

<pre><code>library(data.table)
library(plotly)
library(dplyr)

sample &lt;- data.table(Region=c("Illinois","Illinois","California","California","Texas","Texas"),
                     code=c("IL","IL","CA","CA","TX","TX"),
                     Group=c("A","B"),
                     Value=rnorm(6, mean=100, sd=6))

sample[Region=="Illinois", c('lat', 'long') := list(40.3363, -89.0022)]
sample[Region=="California", c('lat', 'long') := list(36.17, -119.7462)]
sample[Region=="Texas", c('lat', 'long') := list(31.106, -97.6475)]


x &lt;- list(
  scope = 'usa',
  projection = list(type = 'albers usa'),
  showlakes = F,
  lakecolor = toRGB('lightblue')
)

sample %&gt;%
  plot_geo(
    locationmode='USA-states'
  ) %&gt;%
  add_markers(
    y=~lat, x=~long, hoverinfo="text",
    color=~Group,
    text=~Group, size=~Value
  ) %&gt;%
  layout(
    title='plotly marker map',
    geo=x
  )
</code></pre>