How to calculate frequency received data from time column in Power BI? - powerbi

Question

I have a table with received time like the below:
As you see, the frequency of received data in some rows is different and they are 1000ms, 1001ms, 998ms.
How can I calculate the average frequency of received time in ms?

Answer 1

I suggest using Power Query to
add a column that is the original date_time column offset by 1
Then add another column showing the difference between current row and previous row
This method, at least in M Code, is faster than using an Index column to refer to previous row
Then you can do your mathematical analyses.
let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc27DcAgDAXAVRA1An9iO2EVxP5rgEQZXn3FjZGjsTUh4cRdqctTwy3P8heD4lv8KgHl3RJX+dCjBIXRo3JkLg==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [date_time = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"date_time", type datetime}}),
//add column containing previous rows data
//usually faster than using and INDEX column
prevList = {null} & List.RemoveLastN(#"Changed Type"[date_time]),
tbl1 = Table.FromColumns(
{#"Changed Type"[date_time],prevList},
{"date_time","Prev Row"}
),
#"Added Custom" = Table.AddColumn(tbl1, "Difference", each /*if [Prev Row] = null then 0
else*/ Duration.TotalSeconds([date_time] - [Prev Row])),
#"Changed Type1" = Table.TransformColumnTypes(#"Added Custom",{
{"date_time", type datetime}, {"Prev Row", type datetime}, {"Difference", type number}})
in
#"Changed Type1"

Answer 2

In PowerQuery add an Index column to your data so that you can address singe rows. Then with DAX add a calulated column to the table:
Milliseconds =
VAR NextIndex = 'Table'[Index] + 1
VAR MaxIndex = MAX(Table[Index])
VAR Difference =
IF(
'Table'[Index] = MaxIndex,
BLANK(),
'Table'[date_time] -
CALCULATE(
VALUES('Table'[date_time]),
Filter(
ALL('Table'),
'Table'[Index] = NextIndex
)
)
)
RETURN
CONVERT(ABS(Difference * 3600 * 24 * 1000), INTEGER)
Now you are looking for AVERAGE( Milliseconds ).
Note: Things would have been easier if you provided copyable data instead of a screenshot.