title: How to change data points color based on some variable
body: <p>I have 2 variables (x,y) that change with time (t). I want to plot x vs. t and color the ticks based on the value of y. e.g. for highest values of y the tick color is dark green, for lowest value is dark red, and for intermediate values the color will be scaled in between green and red.</p>
  
  <p>Can this be done with matplotlib in python?</p>