I’m trying to exectute a simple conditional evaluation statement. I have a table t listed in tables.
$ [t; [action one]; [action two]
I keep getting a type error. Is there some unique way to use tables in conditional evaluation?? I’ve tried if t not null, t in tables, count t > 0, etc, It keeps giving me the same error. Evaluation works for variables but I can’t get it to recognise the table, and this is the only way I can think to get the function to work.
I just need to check if the table exists. i know this is probably pretty simple i just can’t figure it out.
All help appreciated.
q)$[t in key .;present;missing]
`missing
q)t:(a:0 1)
q)$[t in key .;present;missing]
`present
or with tables cmd
q)$[`t in tables;`present;`missing]
`present
q)delete t from `.;
q)$[`t in tables;`present;`missing]
`missing
You can use .Q.qt also to know if its table or not. It returns bollean result.
On May 12, 2014 12:32 AM, “Daniel o keeffe” <doktordiversity@gmail.com> wrote:
>
> I’m trying to exectute a simple conditional evaluation statement. I have a table t listed in tables.
>
> $ [t; [action one]; [action two]
>
> I keep getting a type error. Is there some unique way to use tables in conditional evaluation?? I’ve tried if t not null, t in tables, count t > 0, etc, It keeps giving me the same error. Evaluation works for variables but I can’t get it to recognise the table, and this is the only way I can think to get the function to work.
>
> I just need to check if the table exists. i know this is probably pretty simple i just can’t figure it out.
>
> All help appreciated.
>
> –
> Submitted via Google Groups
q)a:(a:ab`c;b:1 2 3)
q)
q)
q)a
a b
a 1
b 2
c 3
q)$[a in tables;true;false]
`true
q)
Thanks guys. It was, inevitably, a backtick before the tablename. But I’d still be here clueless if it wasn’t pointed out:)
Just out of interest, the difference between tables in system “a” and system “b”, a being function local and b being global is that about it?? If tables is system “a” I assume there is an alternative command for system “b”? Its just when i define a table in my function I don’t see why it should still be available outside the function, wheras variables are not.
Thanks