Vertical Axis starts from Top (using Data Transform)



I am using D3 0.3.1 version.

I have a line chart it works fine (y axis bottom to top) starts from (0,40) to (24,3000).

Now i am trying to invert the line (y axis top to bottom), this is achieved by using following link ( https://dynamicdatadisplay.codeplex.com/discussions/69390). But the issue i am facing is when it is displayed - y axis shows range from -40 to +40. it has to show only the visible graph area dynamically.

i.e user has to scroll down the y axis from -40 to 40 to view the line graph.

Can you please suggest me a solution for it.

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