You need to add the Comparison like for like as an additionally values in your market-field and then you could query these value, for example:
if(market = 'Comparison like for like', exp1, exp2)
Another approach is to switch to a pivot-chart and adding a further dimension which could be queried with:
if(dimensionality() = 0, exp1, exp2)
A further approach (which I prefer) would be to display only one view at a time - one time the year-comparing overall and one time the cleaned year-comparing. For this you could use two objects maybe within a container - also the use of dimension/expression-groups is a possibility.
Two is better than one ... you give me the trick.. is to create a specific field to do the comparison... and it's fast to implement
Currently, my fact table has two columns : LFL_TY, LFL_LY (both columns has 1 or 0 values, it's calculated during the script load).. thoses two colums works perfectly well for other graphs..
The drawback of my idea... this will only compare Current Year vs Last Year (with the other method LFL_TY, LFL_LY , I can compare in a like for like analysis 2014 to 2013 ...for example)
I think I'll create a specific ComparisonTable to handle my presentation issue. I do not want to use a pivot table because it will be use in a NPrinting report ...