iterate()
Here’s how to use iterate() functions.
A.it erate()
Description:
Perform iterative loop on a record sequence and return the result of the last calculation of a given expression.
Syntax:
A.iterate(x,a,c)
Note:
The function loops through members of record sequence A to calculate expression x and returns the result of the last calculation of x. ~~ represents the previous value of x. Parameter a is the default initial value for each calculation, whose absence indicates a null initial value. Exit the loop once the result of expression c is true.
Parameter:
|
A |
A sequence/record sequence |
|
x |
An expression |
|
a |
The initial value |
|
c |
A Boolean expression |
Option:
|
@a |
Return the results of calculating the expression over every member |
Return value:
Result of expression x
Example:
|
|
A |
|
|
1 |
[2,222,22,122,2222] |
|
|
2 |
=A1.iterate(~*2) |
4444 |
|
3 |
=A1.iterate@a(~*2) |
[4,444,44,244,4444] |
|
4 |
=A1.iterate(~~*2,3) |
96 |
|
5 |
=A1.iterate(~~*2,5,~>500) |
80 |
|
6 |
=demo.query("select * from SALES") |
|
|
7 |
=A6.derive(A6.(AMOUNT).iterate(~~*2,5,~>20000):Cumulation) |
|
Related function:
ch.iterate()
Description:
Syntax:
ch.iterate(x,a,c)
Note:
The function loops through record sequences in channel ch to calculate expression x and returns the result of the last calculation of x. ~~ represents the previous value of x. Parameter a is the default initial value for each calculation, whose absence indicates a null initial value. Exit the loop once the result of expression c is true.
Parameter:
|
ch |
A channel |
|
x |
An expression |
|
a |
Initial value |
|
c |
An expression returns true/false |
Return value:
Result of expression x
Example:
|
|
A |
|
|
1 |
=[2,222,22,122,2222].cursor() |
|
|
2 |
=channel() |
|
|
3 |
=channel() |
|
|
4 |
=A2.iterate(~*2) |
|
|
5 |
=A3.iterate(~~*2,3) |
|
|
6 |
=A1.push(A2,A3) |
|
|
7 |
=A1.fetch() |
|
|
8 |
=A2.result() |
4444 |
|
9 |
=A3.result() |
96 |
|
10 |
=[100,200,800,2000].cursor() |
|
|
11 |
=channel() |
|
|
12 |
=A11.iterate(~~*3,10,~>250) |
|
|
13 |
=A10.push(A11) |
|
|
14 |
=A10.fetch() |
|
|
15 |
=A11.result() |
90 |
cs.iterate()
Description:
Perform iterative loop on record sequences in a cursor and return the result of the last calculation of a given expression.
Syntax:
cs.iterate(x,a,c)
Note:
The function loops through record sequences in cursor cs to calculate expression x and returns the result of the last calculation of x. ~~ represents the previous value of x. Parameter a is the default initial value for each calculation, whose absence indicates a null initial value. Exit the loop once the result of expression c is true.
Parameter:
|
cs |
A cursor |
|
x |
An expression |
|
a |
Initial value |
|
c |
An expression returns true/false |
Return value:
Result of expression x
Example:
|
|
A |
|
|
1 |
=[2,222,22,122,2222].cursor() |
|
|
2 |
=A1.iterate(~*2) |
4444 |
|
3 |
=[2,222,22,122,2222].cursor().iterate(~~*2,3) |
96 |
|
4 |
=[2,222,22,122,2222].cursor().iterate(~~*2,5,~>500) |
80 |
|
5 |
=demo.cursor("select * from SALES") |
|
|
6 |
=A5.(AMOUNT).iterate(~~*2,5,~>20000) |
40 |
iterate ()
Description:
An iterative loop for calculating an expression.
Syntax:
iterate(x,a;Gi,…)
Note:
The function performs an interative loop to compute expression x – which contains a ~~, and returns the result. Each time when the value of field Gi changes, the value of ~~ becomes a. The parameter Gi can be omitted. When parameter a isn’t supplied, its value is null.
Parameter:
|
x |
An expression containing ~~ |
|
a |
Initial value |
|
Gi |
Field name |
Return value:
Value of the given expression
Example:
|
|
A |
|
|
1 |
=demo.query("select top 7 * from SCORES ") |
|
|
2 |
=A1.groups(CLASS:Class,STUDENTID:StudentID;iterate(~~*2): Score1) |
|
|
3 |
=A1.groups(CLASS:Class,STUDENTID:StudentID;iterate(~~*2,10): Score1) |
|
|
4 |
=A1.derive(iterate(~~*2,10;STUDENTID):F1) |
|
Related function: