Make a difference operation between 2 data for Bar Graph

[#1]

Hi Everybody,

I am learning ClikView since yesterday, I read the tutorial so now I am able to import data from xml files , "modify" the script and display bar graph.

Let me explain you what I want to do :

Assume that I have a table named Data which looks like this :

Time Value

00:00:00 10
00:10:00 15
00:20:00 22
...

I would like to display a bar graph likie this :

00:00:00 -> 00:10:00 5 because 15 -10

00:10:00 -> 00:20:00 7 because 22 - 15

and so on

I think I need to add a calculated expression, but I don't know more.

Could you help me please,

Thank you very much !

Jérémy