title: How to independently set horizontal and vertical, major and minor grid lines of a plot?
body: <p>I want to plot major grid lines of y-axis (horizontal grid lines) but I don't want to plot the vertical major grid lines (of x-axis). Instead I want to plot vertical minor grid lines.</p>
  
  <p>How can I do this?</p>
  
  <p>The <code>ax.grid(which='major', linewidth=0)</code> code hides both vertical and horizontal major grid lines...</p>
  
  <p>Thank you!</p>