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Post Prodigy

## Transform a date to year-month

I have a question and i need your help.

I have a column with dates in the following format 3-2-2017 07:49:00 and i want to transform that to a year-weeknumber for example 2017-05.

My formula can get the year and month correctly but then it reads 2017-5 and it leaves the extra 0 because i want it to read 2017-05

If i do not get the extra 0 my visual will place the values wrong.

Because you get:

2016-1 - 2016-10 - 2016-11 - 2016-2 - 2016-3

2016-1 - 2016-2 - 2016-3 - 2016-10 - 2016-11

That is why i need the extra 0, so i can get:

2016-01 - 2016-02 - 2016-03 - 2016-10 - 2016-11

I hope you guys understand what i am trying to do

Binnenkomst Ticket = Tickets[Startdatum].[Year]&"-"&Tickets[Startdatum].[MonthNo]

2 ACCEPTED SOLUTIONS
Community Champion

@RvdHeijden

`Year-Mon = FORMAT('Table'[Date], "YYYY-MM")`

Good Luck!

Community Champion

@RvdHeijdenHere's DAX

```Year-Wk =
YEAR ( 'Calendar'[Date] ) & "-"
& CONCATENATE (
IF ( WEEKNUM ( 'Calendar'[Date] ) < 10, "0", "" ),
WEEKNUM ( 'Calendar'[Date] )
)```

Yes you may have to adjust WEEKNUM depending on when your week starts SUN (1) on MON (2)

I have skipped this optional parameter because the default is 1 which is what i need.

Hope this helps.

Good Luck!

14 REPLIES 14
Community Champion

Just in case you mean week number (as you mention in your example) instead of month number, and because I spot some Dutch in your coding, the code below is a M function (Power Query / Query Editor) that wll return the ISO Week Number, based on a date.

```let
Source = (DateParameter as date) => let
Jan1 = #date(Date.Year(Thursday),1,1),
Days = Number.From(Thursday - Jan1),
Result = Number.RoundDown(Days/7)+1
in
Result
in
Source```

This will only return the week number.

If you want year-week number, replace the "Result = ..."  line by:

`    Result = Text.From(Date.Year(Thursday))&"-"&Text.PadStart(Text.From(Number.RoundDown(Days/7)+1),2,"0")`
Specializing in Power Query Formula Language (M)
Post Prodigy

@MarcelBeug your right, i was to fast and however @Sean formula works it returns year-month instead of year-weeknumber

But i do not fully understand your formula Marcel.

Im a relative nooby as it comes to these types of formula. Can you give me the complete formula so i can copy/paste is in PowerBi ?

Community Champion

Well, the formula is actually incorporated in the funtion.

I'm not experienced with DAX, but I can provide the rules for ISO week number and the translation of the function steps in English.

Rules for ISO week number:
1. First day of the week is Monday.
2. Each week from Monday to Sunday has the same week number.
3. Week 1 of the year is the week with the first Thursday of the year,
meaning more than half of the days of the week are in week 1.
If January 1st is on Monday-Wednesday 0-2, it will be week 52 or 53 of the preceding year.
If January 1st is on Thursday-Sunday 3-6, it will be week 1 of the current year.

Steps to determine ISO week number:
1. Determine the date of Thursday of the current week.
2. Determine January 1st of the date from step 1.
3. Calculate the number of days from January 1st to the date from step 1.
4. Divide the number of days from step 3 by 7, round down and add 1.

Specializing in Power Query Formula Language (M)
Post Prodigy

@MarcelBeug i know the ISO formula in excel but DAX is different and im not experienced enough with DAX to make a formula based on your info sorry but i really appreciate the help

Does anyone know how to create the formula based on MarcelBeugs info ?

Community Champion

@RvdHeijdenHere's DAX

```Year-Wk =
YEAR ( 'Calendar'[Date] ) & "-"
& CONCATENATE (
IF ( WEEKNUM ( 'Calendar'[Date] ) < 10, "0", "" ),
WEEKNUM ( 'Calendar'[Date] )
)```

Yes you may have to adjust WEEKNUM depending on when your week starts SUN (1) on MON (2)

I have skipped this optional parameter because the default is 1 which is what i need.

Hope this helps.

Good Luck!

Post Prodigy

@Sean

i want the week to start on a monday so where should i place this variable in the formula ?

Year-Wk = YEAR ( 'Calendar'[Date] ) & "-" & CONCATENATE ( IF ( WEEKNUM ( 'Calendar'[Date] ) < 10, "0", "" ), WEEKNUM ( 'Calendar'[Date] ) )

Community Champion

Refering to my previous post, I would guess

Year-Wk = YEAR ( 'Calendar'[Date] ) & "-" & CONCATENATE ( IF ( WEEKNUM ( 'Calendar'[Date],21 ) < 10, "0", "" ), WEEKNUM ( 'Calendar'[Date] , 21) )

But I'm not a DAX expert.

Otherwise, in ISO you can't just take the year from the date, e.g. Sunday 1/1/2017 is week 2016-52 and Monday 12/31/2018 is week 2019-01.

If you can just have my M-formula translated to DAX (or just use the M-solution), then you're good.

Specializing in Power Query Formula Language (M)
Post Prodigy

Wow....thanks again @Sean that did the trick

Community Champion

Sorry, but I'm afraid not. Probably the DAX week number does NOT return the ISO Week number (unless I'm terribly mistaking as I'm not a DAX expert).

Specializing in Power Query Formula Language (M)
Community Champion

It seems that you can supply 21 as second parameter to the WEEKNUM Function to obtain the ISO Week Number, see comments below Microsofts documenetation.

Specializing in Power Query Formula Language (M)
Community Champion

@RvdHeijden

`Year-Mon = FORMAT('Table'[Date], "YYYY-MM")`

Good Luck!

Regular Visitor

How is this supposed to be used in the context of the query?

I tried adding this to a Table.AddColumn() clause as the last argument and it doesnt recognised FORMAT, What am I missing?

Regular Visitor

Hi Sean,

I am trying to create a custom column to extract year/month from my date which is currently in the following format: 01/01/2017 but when I use the formula below, I recieve a 'Token Literal Expected' error for the 'Table' piece.

=FORMAT('Table'[Date], "YYYY-MM")

Also, if I try and use basic functions such as CONCATENATE, FORMAT, MONTH, YEAR, etc, I get an error that Power BI does not recognize the function. Thanks for the advice!

Post Prodigy

@Sean

Your 2 for 2, thanks a bunch, this works

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