title: scatter plots in seaborn/matplotlib with point size and color given by continuous dataframe column
body: <p>I would like to make a scatter plot in seaborn/matplotlib where the size of points is determined by a (continuous) value in a dataframe, and the color of points is also determined by the continuous value of another column in dataframe. In ggplot, the way to do it is:</p>
  
  <pre><code>ggplot(iris) + geom_point(aes(x=Sepal.Width, y=Sepal.Length, size=Petal.Width, color=Petal.Length))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/hUTpz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/hUTpz.png" alt="enter image description here"></a>
  (color/size here are continuous not categorical values)</p>
  
  <p>what's the syntax for this in seaborn/matplotlib?</p>