Decimal Places by Condition

[k-mambo]

Table Example

start_date                    val       
----------------------------------------
2022.05.02D07:36:35.901000000 0.01      
2022.05.02D07:36:36.341000000 0.0125    
2022.05.02D07:36:36.756000000 0.01234568
2022.05.02D07:36:37.204000000 0.9999    
2022.05.02D07:36:37.636000000 0.008     

Desired Result

start_date                    val       
----------------------------------------
2022.05.02D07:36:35.901000000 0.01      
2022.05.02D07:36:36.341000000 0.013    
2022.05.02D07:36:36.756000000 0.012
2022.05.02D07:36:37.204000000 1    
2022.05.02D07:36:37.636000000 0.008     

I tried follows.

@[meter;`val;.Q.f[3]']
start_date                    val    
-------------------------------------
2022.05.02D07:36:35.901000000 "0.010"
2022.05.02D07:36:36.341000000 "0.013"
2022.05.02D07:36:36.756000000 "0.012"
2022.05.02D07:36:37.204000000 "1.000"
2022.05.02D07:36:37.636000000 "0.008"

How do I create a function to represent the desired result?

The \P is set to zero.

[SJT · Accepted solution]

q)show val:.01 .0125 .01234568 .9999 .008
0.01 0.0125 0.01234568 0.9999 0.008
q).001*floor .5+1000*val
0.01 0.013 0.012 1 0.008

More generally, as a function which takes number of decimal places as its left argument:

q){%[;s]floor .5+y*s:10 xexp x}[3]val
0.01 0.013 0.012 1 0.008

Slightly less obviously you can elide floor .5+ with a faster Cast:

q){%[;s]"i"$y*s:10 xexp x}[3]val
0.01 0.013 0.012 1 0.008

[k-mambo]

Thanks!