Calculate sum by grouping dates into weeks in Power BI - sum

Question

I have a 'Date' column and its data type is of date format. There is also another column 'Amount' tied to each date. How can I create new columns representing the sum of total amount collected each 'week' based on each day of the 'Date' column? The 'week' needs to be derived from 'Date' column by grouping the first 7 dates into week 1, next 7 dates into week 2 and so on. Basically I need to show week over week comparison in a chart for different categories in different years for which I need to prepare my data.
I'm providing a sample dataset below to provide a better understanding:
| Categ | Date | Amount |
|-------|------------|--------|
| abc | 11/29/2019 | $1 |
| abc | 11/30/2019 | $2 |
| abc | 12/1/2019 | $3 |
| abc | 12/2/2019 | $3.5 |
| abc | 12/3/2019 | $0 |
| abc | 12/4/2019 | $6 |
| abc | 12/5/2019 | $4 |
| abc | 12/6/2019 | $6.5 |
| abc | 12/7/2019 | $4.5 |
| xyz | 11/29/2019 | $3 |
| xyz | 11/30/2019 | $2 |
| xyz | 12/01/2019 | $4.5 |
| xyz | 12/02/2019 | $8 |
| xyz | 12/03/2019 | $2 |
| xyz | 12/04/2019 | $4 |
| xyz | 12/05/2019 | $2.5 |
| xyz | 12/06/2019 | $9 |
| xyz | 12/07/2019 | $6 |
| abc | 11/29/2020 | $0.5 |
| abc | 11/30/2020 | $3.5 |
| abc | 12/01/2020 | $2 |
| abc | 12/02/2020 | $6 |
| abc | 12/03/2020 | $7 |
| abc | 12/04/2020 | $5 |
| abc | 12/05/2020 | $3 |
| abc | 12/06/2020 | $4 |
| abc | 12/07/2020 | $2 |
I'm expecting my final table to look either like Table 1 or Table 2 provided below:
TABLE 1:
| Categ | Year | Week1 | Week2 |
|-------|------|-------|-------|
| abc | 2019 | $19.5 | $30.5 |
| abc | 2020 | $27 | $6 |
| xyz | 2019 | $26 | $15 |
TABLE 2:
| Categ | Week 1 - 2019 | Week 2 - 2019 | Week 1 - 2020 | Week 2 - 2020 |
|-------|---------------|---------------|---------------|---------------|
| abc | $19.5 | $30.5 | $27 | $6 |
| xyz | $26 | $15 | - | - |

Answer 1

First off, your sample seems to have detail data that adds to 104.5 while the summary adds to 124.0 so something is off there
Beyond that, its a question of date math. Find the year using custom column with formula
= Date.Year([Date])
Find the lowest date and year using
MinDate= Table.Min(#"PreviousStepName", "Date")[Date],
MinYear= Table.Min(#"PreviousStepName", "Year")[Year],
The week numbers you want are (date)-(MinimumDate) - (year-MinimumYear)*365 - (year-MinimumYear) or in code, the formula below in a custom column
= Number.From([Date]) - Number.From(MinDate) -([Year]-MinYear)*365 -([Year]-MinYear)
that math gives you this far right column
Then integer.divide that column results by 7 and add 1. That give you this
remove extra columns, pivot, and done. Sample code for desired output #1 below
let Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}}),
#"Added Custom1" = Table.AddColumn(#"Changed Type", "Year", each Date.Year([Date])),
MinDate = Table.Min(#"Added Custom1", "Date")[Date],
MinYear = Table.Min(#"Added Custom1", "Year")[Year],
#"Added Custom2" = Table.AddColumn(#"Added Custom1", "Week", each Number.From([Date]) - Number.From(MinDate) -([Year]-MinYear)*365 -([Year]-MinYear) ),
#"Integer-Divided Column" = Table.TransformColumns(#"Added Custom2", {{"Week", each 1+Number.IntegerDivide(_, 7), Int64.Type}}),
#"Removed Columns" = Table.RemoveColumns(#"Integer-Divided Column",{"Date"}),
#"Pivoted Column" = Table.Pivot(Table.TransformColumnTypes(#"Removed Columns", {{"Week", type text}}, "en-US"), List.Distinct(Table.TransformColumnTypes(#"Removed Columns", {{"Week", type text}}, "en-US")[Week]), "Week", "Amount", List.Sum)
in #"Pivoted Column"