Finding the difference between values based on month

[Roisin_Cooke19]

Hi 

I have a column containing sensor values at the start of each month.

e.g. 

equipment	month	sensor value
001	jan-2019	1000
001	feb-2019	1100
001	mar-2019	1150
002	jan-2019	2000
002	feb-2019	2250
002	mar-2019	2600

I want to obtain the difference between the sensor value of each month for each equipment.

The results should be as follows:

equipment	month	monthly hours
001	jan-2019	100
001	feb-2019	50
001	mar-2019	-
002	jan-2019	250
002	feb-2019	350
002	mar-2019	-

Does anyone know how to do this in the data load editor?

Thanks,

Roisin

[tresesco · Accepted solution]

Try like:

t1:
LOAD equipment, 
     date#(month, 'MMM-YYYY') as month, 
     [sensor value]
FROM
[https://community.qlik.com/t5/New-to-Qlik-Sense/Finding-the-difference-between-values-based-on-month/td-p/1674704]
(html, utf8, UserAgent is 'Mozilla/5.0', embedded labels, table is @1);

t2:
Load
	*,
	If(equipment=peek(equipment), RangeSum(-[sensor value],peek([sensor value]))) as [monthly hours]
Resident t1 order by equipment, month Desc;

Drop Table t1;	

[Roisin_Cooke19]

Thank you very much for your help Tresesco, that worked perfectly! 

Regards,

Roisin