Using JMP - SAS

398 Formula Functions Reference Appendix B
Row Functions
Lag
Returns the value of the first argument in the row defined by the current row less the second argument. The
default Lag is one, which you can change to any number. The value returned for any lag that identifies a
row number less than one is missing. Note that Lag(X, n) gives the same result as the subscripted
notation, X Row( )–n .
Dif
Returns the difference between the value of the first argument in the current row and its value in the row
defined by the current row less the second argument. The default Dif is one, which you can change to any
number. Note that Dif(X, n) gives the same result as X Row() –X Row()-n , or as X Row() –Lag(X, n).
Subscript
Enables you to use a column’s value from a row other than the current row. After choosing Subscript from
the list, enter a numeric expression into the subscript argument. Subscripts that evaluate to nonexistent row
numbers produce missing values. Column names with no subscript refers to the current row. To remove a
subscript, select the subscript and delete it. Then delete the missing box.
The formula Count Row() – Count Row()–1 , where Row() is the row number as described below, uses
subscripts to calculate the difference between each pair of values from the column named Count. This result
is the same as that given by the Dif() function. When Row() is 1, the computation produces a missing value.
The formula below calculates a column called Fib, which contains the terms of the Fibonacci series (each
value is the sum of the two preceding values in the calculated column).
It shows the use of subscripts to do recursive calculations. A recursive formula includes the name of the
calculated column, subscripted such that it references only previously evaluated rows (rows 1 through (i–1)).
The calculation of the Fibonacci series shown includes a conditional expression and a comparison. See the
sections “Conditional Functions” on page 412, and “Comparison Functions” on page 411, for details.
Row
Returns the current row number when an expression is evaluated for that row. You can use Row() in any
expression, including column name subscripts. The default subscript of a column name is Row() unless
otherwise specified.
NRow
Returns the total number of rows in the active data table.