Thanks for the reply. It makes sense. Now I have different issues. Please check https://jsfiddle.net/cancanvas/Loab2h6L/17/
Question1: Why the legend of series 2 and 3 dose NOT show dot/dash line? I need to make it consistent with the chart.
Question2: Is there any way I can group legend make stype them separately. e.g. I want to make series 1, 2,3 legend virtically aligned to the left bottom and label 1 and 2 vertically aligned to the right bottom.
Question3: All my data has integer as x value, why it automatically calculated to interval as 0.5? I cannot specify interval to a specific integer because it is dynamic based on data comes in. But I need x value always calculated and displayed as integer. How can I implement this?
Thank you very much!