Calculation % of value for a date vs previous date

[Anonymous]

Hello Guys

Please help me with a DAX solution for this case:

I have a table where for 3 phases i calculate some values wach week.

I want to make the % vs last week value for each phase.I this example to have the value of Phase A from 01/14/2022 divided to the value of Phase A from 01/08/2022. 

Thank you

Date	Phase	Value
1/1/2022	A	100
1/1/2022	B	200
1/1/2022	C	300
1/8/2022	A	110
1/8/2022	B	210
1/8/2022	C	310
1/14/2022	A	120
1/14/2022	B	220
1/14/2022	C	330

[amitchandak · Accepted solution]

@ , Create a separate date/week table along with week rank. Once you create a last week using that table, it will take care each phase get their last week

example

new columns  in date/week table
Week Start date = 'Date'[Date]+-1*WEEKDAY('Date'[Date],2)+1
Week End date = 'Date'[Date]+ 7-1*WEEKDAY('Date'[Date],2)
Week Rank = RANKX(all('Date'),'Date'[Week Start date],,ASC,Dense)
OR
Week Rank = RANKX(all('Date'),'Date'[Year Week],,ASC,Dense) //YYYYWW format

measures using your table
This Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])))
Last Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])-1))

Power BI — Week on Week and WTD
https://medium.com/@amitchandak.1978/power-bi-wtd-questions-time-intelligence-4-5-98c30fab69d3
https://community.powerbi.com/t5/Community-Blog/Week-Is-Not-So-Weak-WTD-Last-WTD-and-This-Week-vs-La...
https://www.youtube.com/watch?v=pnAesWxYgJ8