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SEQUENTIAL DIFFERENCEName:
If there are less than two points in the series, nothing will be done. One use of sequential differencing is to remove trend from time series data. The 2016/02 version of Dataplot generalized this command in the following two ways.
where <x> is the response variable; <stat> is one of
SUM PRODUCT MEAN MINIMUM MAXIMUM LOWER UPPER; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
<SUBSET/EXCEPT/FOR qualification> where <y> is the response variable; <x> is a the group-id variable; <stat> is one of
SUM PRODUCT MEAN MINIMUM MAXIMUM LOWER UPPER; <x2> is a variable containing the group-id of the differenced series; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
LET XD = SEQUENTIAL MEAN PRESSURE LET XD = SEQUENTIAL SUM PRESSURE LET XD = SEQUENTIAL DIFFERENCE PRESSURE SUBSET X > 4 LET YDIFF X2 = SEQUENTIAL DIFFERENCE Y X
SEQUENTIAL AVERAGE is a synonym for SEQUENTIAL MEAN SEQUENTIAL MIN is a synonym for SEQUENTIAL MINIMUM SEQUENTIAL MAX is a synonym for SEQUENTIAL MAXIMUM
2016/02: Support for SUM, PRODUCT, MEAN 2016/02: Support for MINIMUM, MAXIMUM, LOWER, and UPPER 2016/02: Support for group-id variable< LET X1 = DATA 12 4 2 3 9 7 LET XD = SEQUENTIAL DIFFERENCE X1The variable XD will contain the following values:
. Step 1: Define the data . let y = sequence 1 1 10 . . Step 2: Compute the sequential statistics . let ydiff = sequential difference y let ysum = sequential sum y let yprod = sequential product y let ymean = sequential mean y let ymin = sequential min y let ymax = sequential max y . . Step 3: Print the results . set write decimals 1 print y ydiff ysum yprod ymean ymin ymaxThe following output is generated. ------------------------------------------------------------ Y YDIFF YSUM YPROD ------------------------------------------------------------ 1.0 1.0 3.0 2.0 2.0 1.0 5.0 6.0 3.0 1.0 7.0 12.0 4.0 1.0 9.0 20.0 5.0 1.0 11.0 30.0 6.0 1.0 13.0 42.0 7.0 1.0 15.0 56.0 8.0 1.0 17.0 72.0 9.0 1.0 19.0 90.0 10.0 0.0 0.0 0.0 ------------------------------------------------------------ Y YMEAN YMIN YMAX ------------------------------------------------------------ 1.0 1.5 1.0 2.0 2.0 2.5 2.0 3.0 3.0 3.5 3.0 4.0 4.0 4.5 4.0 5.0 5.0 5.5 5.0 6.0 6.0 6.5 6.0 7.0 7.0 7.5 7.0 8.0 8.0 8.5 8.0 9.0 9.0 9.5 9.0 10.0 10.0 0.0 0.0 0.0Program 3: . Step 1: Define the data . dimension 40 columns let y = sequence 1 1 10 let x = sequence 1 5 1 2 . . Step 2: Compute the sequential statistics . let ydiff ygroup = sequential difference y x let ysum ygroup = sequential sum y x let yprod ygroup = sequential product y x let ymean ygroup = sequential mean y x let ymin ygroup = sequential min y x let ymax ygroup = sequential max y x let ylow ygroup = sequential lower y x let yupp ygroup = sequential upper y x . . Step 3: Print the results . set write decimals 1 print ygroup ydiff ysum yprod ymean ymin ymax ylow yuppThe following output is generated. --------------------------------------------------------------------------- YGROUP YDIFF YSUM YPROD YMEAN --------------------------------------------------------------------------- 1.0 1.0 3.0 2.0 1.5 1.0 1.0 5.0 6.0 2.5 1.0 1.0 7.0 12.0 3.5 1.0 1.0 9.0 20.0 4.5 2.0 1.0 13.0 42.0 6.5 2.0 1.0 15.0 56.0 7.5 2.0 1.0 17.0 72.0 8.5 2.0 1.0 19.0 90.0 9.5 --------------------------------------------------------------------------- YGROUP YMIN YMAX YLOW YUPP --------------------------------------------------------------------------- 1.0 1.0 2.0 1.0 2.0 1.0 2.0 3.0 2.0 3.0 1.0 3.0 4.0 3.0 4.0 1.0 4.0 5.0 4.0 5.0 2.0 6.0 7.0 6.0 7.0 2.0 7.0 8.0 7.0 8.0 2.0 8.0 9.0 8.0 9.0 2.0 9.0 10.0 9.0 10.0
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Date created: 02/26/2016 |