Calculate % change from previous column

[zawlh]

Hello everyone, I am new to Power BI. We used Postgres data from our chatbot system. 

So this is our chatbot result. I would like to calculate % change with line value showing how many % of user drop/jump in each day.
Can anyone help with me.
Database is like that

[az38]

Hi @zawlh 

please, provide your desired output more accurace.

what is "how many % of user drop/jump in each day" ?

what is the total users? total by day, total cummulative or smth? How exactly calculate it? maybe you can display an example

where is users field in your data model?

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[zawlh]

@az38  the number is the distinctcount of messengerID. I want percent difference from previous column(column from chart). (For eg. 38% drop from day01-begin to day01-end (assuming day01-begin is 100%). Could you solve it ?

[az38]

@zawlh 

its still not almost clear but try to create a measure like

Measure = 
var _prevDayNumberStart = CALCULATE(MAX('Table'[Day Number]), FILTER(ALL('Table'), 'Table'[timestamp] < SELECTEDVALUE('Table'[timestamp]) && CONTAINSSTRING('Table'[Day Number],"begin"))
var _prevDayTimestamp = CALCULATE(MAX('Table'[timestamp]), 'Table'[Day Number]=_prevDayNumberStart)

RETURN
DIVIDE( CALCULATE(DISTINCTCOUNT('Table'[messenger_id]), FILTER(ALL('Table'), 'Table'[timestamp] < SELECTEDVALUE('Table'[timestamp])), CALCULATE(DISTINCTCOUNT('Table'[messenger_id]), FILTER(ALL('Table'), 'Table'[timestamp] < _prevDayTimestamp) )

not sure, it will work, need to check 

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[zawlh]

@az38  I will show you database
I cannot use the formula you provide unless you don't know exactly about my data 

sorry for confidential data

[az38]

@zawlh 

distinct count of users should be calculate for a day or for the whole period before the day?

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[zawlh]

@az38  for each day. And I want to see how many percent of users have dropped. Day Number is just alternate name of attribute. There are too many attribute in chatbot. But I only need some attribute and I have to change the name with another column 

[az38]

@zawlh 

and how do you calculate count of users in day-begin point?

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[zawlh]

@az38  I used Day Number is X-axis and DISTINCTCOUNT of messenger_id in value(so not difficult). What makes me difficult is the percent change in each day

The above graph is the example

[az38]

@zawlh 

try a measure like this

Measure = 
var _currentContextDay = DATE(YEAR(SELECTEDVALUE('Table'[timestamp]));MONTH(SELECTEDVALUE('Table'[timestamp]));DAY(SELECTEDVALUE('Table'[timestamp])))
var _countCurDay = CALCULATE(DISTINCTCOUNT('Table'[messenger_id]);FILTER(ALL('Table');'Table'[timestamp].[Date]=_currentContextDay))
var _countLastDay = CALCULATE(DISTINCTCOUNT('Table'[messenger_id]);FILTER(ALL('Table');_currentContextDay=DATEADD('Table'[timestamp].[Date];1;DAY)))
return 
1-DIVIDE(_countLastDay;_countCurDay)

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[zawlh]

@az38  I am sorry. Because of my bad English writing, I think you misunderstand something. I want X-axis to be Day Number(day01-begin,day01-end,day02-begin,.....). The percent change I want is how many percent of users have dropped from day01 to day02 to day03 to ........

Thanks for your patience and guiding. 
I hope you can help me with this.

[az38]

@zawlh 

look here https://ufile.io/lvak35gl 

simple example which looks like you need (as I think)

do not hesitate to give a kudo to useful posts and mark solutions as solution

[zawlh]

@az38  Bro your formula makes some progress. But I still have some problems. Could you help with me please. My measure show only 0%
. 
I used the same exact formula with yours, using my original table name.