Changing average using slicer

[hejszyszki]

Hi! Below i have a graph, made of measure below which shows 4-w Average. (Material code has relationship with area in another table to be clear).  Structure of table is also shown below. Weeks are like from 1 to 78 (W1 - W78). What i would like to accomplish is to make slicer(with slider/zip) that shows range from W1 to last Week and once you pick certain range like W2-W8 it shows average of W2-W8. 
Does anyone have any idea how to do it? Is it even possible to do :)?

Thanks in advance!

[Fowmy]

@hejszyszki 
The best approach to your problem is to unpivot your Weeks into two columns as follows

Material Code, Desc, SNP Plan, Week, Value

Refer to these videos on UnPivot: https://www.youtube.com/watch?v=Vff2kRBM95o&t=0s 

[hejszyszki]

Ended up with something like this. Stuck when trying to create slicer of average of picked range.
Thanks in advance!

[Fowmy · Accepted solution]

@hejszyszki 

You need to create another column in this table to extract the week number.

WeekNumber = INT(SUBSTITUTE(Table12[WeekNum],"W",""))

Then, you can use below measure and make sure you have slicer on the WeekNumber to select the range:

measure =
VAR __minweekno =
    MIN ( 'invo dos'[WeekNumber] )
VAR __maxnweekno =
    MAX ( 'invo dos'[WeekNumber] )
RETURN
    SUMX (
        FILTER (
            'invo dos',
            'invo dos'[SNP Plan] = "Short Supply"
                && 'invo dos'[WeekNumber] >= __minweekno
                && 'invo dos'[WeekNumber] <= __maxnweeknow
        ),
        'invo dos'[Value]
    )

Note: If your data expands into more than one year then you will have to add (Year + weekNumber )