Substract Previous row

[naveen_85]

Hello Team,

i have the below table in power BI, so i need to calculate the below formula by using the below table. much appreciated if you could help on the below.

i need to substract with previous row (C2-B2) if satisfies thn it will call (C3-(C2-B2))/C2,C3/C2).

=IF((C2-B2)>0,(C3-(C2-B2))/C2,C3/C2)

Data refers in excel file as below;

C2 = 133

B2 = 128

C3 = 10 ( New Hired Column)

Month	Total Payroll	New Hired	Total temporary
202106	128	11	11
202107	133	10	15
202108	135	12	13
202109	140	14	10

[v-jingzhang · Accepted solution]

Hi @naveen_85 

You can first add an Index column which starts at 0 (this column will be used like row number in the following step). Then add a custom column with below code. "Added Index" is the previous step name. Modify it according to your transformation steps. 

let 
  previousTotal = #"Added Index"{[Index]-1}[Total Payroll],
  diffTotal = [Total Payroll] - previousTotal
in 
  if diffTotal > 0 then ([New Hired]-diffTotal)/[Total temporary] else [New Hired]/[Total Payroll]

There is an error in the first row because it doesn't have a previous row. You can replace error value with Replace Errors feature under Transform tab > Replace Values. You can format the numbers in the custom column per your need. 

Regards,
Community Support Team _ Jing
If this post helps, please Accept it as the solution to help other members find it.

[lbendlin]

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjIwMjQwU9JRMjSyAJGGECJWByplDuIbG4NIAxBhipACqzc2BesFMxFSliC+CViDCURrbCwA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Month = _t, #"Total Payroll" = _t, #"New Hired" = _t, #"Total temporary" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Total Payroll", Int64.Type}, {"New Hired", Int64.Type}, {"Total temporary", Int64.Type}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "Custom", each if [Total Payroll]-#"Changed Type"[Total Payroll]{[Index]-1} > 0 then [New Hired]-[Total Payroll]+#"Changed Type"[Total Payroll]{[Index]-1} else [New Hired]/[Total Payroll])
in
    #"Added Custom"

Note:  your teminology is unusual. Usually rows have numbers and columns have letters.