EARLIER Function (DAX)

 

Returns the current value of the specified column in an outer evaluation pass of the mentioned column.

EARLIER is useful for nested calculations where you want to use a certain value as an input and produce calculations based on that input. In Microsoft Excel, you can do such calculations only within the context of the current row; however, in DAX you can store the value of the input and then make calculation using data from the entire table.

EARLIER is mostly used in the context of calculated columns.

EARLIER(<column>, <number>)  

Parameters

TermDefinition
columnA column or expression that resolves to a column.
num(Optional) A positive number to the outer evaluation pass.

The next evaluation level out is represented by 1; two levels out is represented by 2 and so on.

When omitted default value is 1.

The current value of row, from column, at number of outer evaluation passes.

Description of errors

EARLIER succeeds if there is a row context prior to the beginning of the table scan. Otherwise it returns an error.

The performance of EARLIER might be slow because it theoretically, it might have to perform a number of operations that is close to the total number of rows (in the column) times the same number (depending on the syntax of the expression). For example if you have 10 rows in the column, approximately a 100 operations could be required; if you have 100 rows then close to 10,000 operations might be performed.

System_CAPS_ICON_note.jpg Note


In practice, the xVelocity in-memory analytics engine (VertiPaq) performs optimizations to reduce the actual number of calculations, but you should be cautious when creating formulas that involve recursion.

To illustrate the use of EARLIER, it is necessary to build a scenario that calculates a rank value and then uses that rank value in other calculations.

The following example is based on this simple table, ProductSubcategory, which shows the total sales for each ProductSubcategory.

The final table, including the ranking column is shown here.

ProductSubcategoryKeyEnglishProductSubcategoryNameTotalSubcategorySalesSubcategoryRanking
18Bib-Shorts$156,167.8818
26Bike Racks$220,720.7014
27Bike Stands$35,628.6930
28Bottles and Cages$59,342.4324
5Bottom Brackets$48,643.4727
6Brakes$62,113.1623
19Caps$47,934.5428
7Chains$8,847.0835
29Cleaners$16,882.6232
8Cranksets$191,522.0915
9Derailleurs$64,965.3322
30Fenders$41,974.1029
10Forks$74,727.6621
20Gloves$228,353.5812
4Handlebars$163,257.0617
11Headsets$57,659.9925
31Helmets$451,192.319
32Hydration Packs$96,893.7820
21Jerseys$699,429.787
33Lights36
34Locks$15,059.4733
1Mountain Bikes$34,305,864.292
12Mountain Frames$4,511,170.684
35Panniers36
13Pedals$140,422.2019
36Pumps$12,695.1834
2Road Bikes$40,551,696.341
14Road Frames$3,636,398.715
15Saddles$52,526.4726
22Shorts$385,707.8010
23Socks$28,337.8531
24Tights$189,179.3716
37Tires and Tubes$224,832.8113
3Touring Bikes$13,334,864.183
16Touring Frames$1,545,344.026
25Vests$240,990.0411
17Wheels$648,240.048

One way to obtain a rank value for a given value in a row is to count the number of rows, in the same table, that have a value larger (or smaller) than the one that is being compared. This technique returns a blank or zero value for the highest value in the table, whereas equal values will have the same rank value and next value (after the equal values) will have a non consecutive rank value. See the sample below.

A new calculated column, SubCategorySalesRanking, is created by using the following formula.

= COUNTROWS(FILTER(ProductSubcategory, EARLIER(ProductSubcategory[TotalSubcategorySales])<ProductSubcategory[TotalSubcategorySales]))+1  

The following steps describe the method of calculation in more detail.

  1. The EARLIER function gets the value of TotalSubcategorySales for the current row in the table. In this case, because the process is starting, it is the first row in the table

  2. EARLIER([TotalSubcategorySales]) evaluates to $156,167.88, the current row in the outer loop.

  3. The FILTER function now returns a table where all rows have a value of TotalSubcategorySales larger than $156,167.88 (which is the current value for EARLIER).

  4. The COUNTROWS function counts the rows of the filtered table and assigns that value to the new calculated column in the current row plus 1. Adding 1 is needed to prevent the top ranked value from become a Blank.

  5. The calculated column formula moves to the next row and repeats steps 1 to 4. These steps are repeated until the end of the table is reached.

The EARLIER function will always get the value of the column prior to the current table operation. If you need to get a value from the loop before that, set the second argument to 2.

EARLIEST Function (DAX)
Filter Functions (DAX)

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