apply the function, pass the return value to the function again, multiple rounds

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apply the function, pass the return value to the function again, multiple rounds

Posted by matt_fang on April 16, 2022 at 12:00 am
I have a list of symbols, say `A`B`C. I have a table tab0; A function that takes in a table plus a string as arguments.
```
tab1: f[tab0;`A] tab2: f[tab1;`B] tab3: f[tab2;`C] 
```
I only care about the final values. But my list of symbols can be long and can have variable length, so I don’t want to hardcode above. How do I achieve it?

I think it has something to do with https://code.kx.com/q/ref/accumulators/ but I really struggle to figure out the syntax.
matt_fang replied 8 months ago 2 Members · 1 Reply
1 Reply

rocuinneagain

Member

April 17, 2022 at 12:00 am

You can so this using over

q)tab:([] A:1 2 3;B:4 5 6;C:7 8 9) 
// Sample table 

q)tab 
A B C 
----- 
1 4 7 
2 5 8 
3 6 9 

q)func:{![x;();0b;enlist[y]!enlist (+;y;1)]} 
//Function I want to run 

q)func[tab;`A] // Same as: update A:A+1 from tab 
A B C 
----- 
2 4 7 
3 5 8 
4 6 9 

q)func over enlist[tab],`A`B`C // Using over accumulator 
A B C 
------ 
2 5 8 
3 6 9 
4 7 10

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apply the function, pass the return value to the function again, multiple rounds

rocuinneagain