How do I filter a non-integer list?

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1

I’m looking for the equivalent of “where” that can be applied to listsof arbitrary types. For example suppose I havex: string each 100 101 102 202 103 1004 1005How would I filter this to return only strings of length 4 or greater?

2

To: personal-kdbplus@googlegroups.com
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then you should use the where function

q)x where 4<=count each x
“1004”
“1005”

Regards,
Attila
On 1 Nov 2011, at 20:41, Don Nguyen wrote:

> I’m looking for the equivalent of “where” that can be applied to lists
> of arbitrary types. For example suppose I have
>
> x: string each 100 101 102 202 103 1004 1005
>
> How would I filter this to return only strings of length 4 or greater?
>
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3

To: personal-kdbplus@googlegroups.com
X-Mailer: Apple Mail (2.1084)

> x: string each 100 101 102 202 103 1004 1005
>
> How would I filter this to return only strings of length 4 or greater?

“where” works (in this sense) on any boolean vector

apply your test, apply where, apply back to the list

q)x where 4<=count each x
“1004”
“1005”

as a function, you could write

q)filter:{y where x y}
q)filter[4<=count each]x
“1004”
“1005”