Evolution of a price : how to not display values that doesn't change ?

[#1]

Hi !

I have a table with :

- a date

- a price

I want to make a graph that displays the evolution of the prices, displaying only the date where the value changes.

I made a "if (above(price) <> price, price)" that almost works, except the "above" function remove the "remove null values" option.

I've a huge list of dates, with only few values.

I want a list of few dates, with the values.

Does anyone has an idea ?