Hi,
I wonder if there is a way to select a single element from a list, for example…
date time prc vol bPrc1
2014.01.02 09:25:05.000 9.44 1461700 9.43 9.42 9.41 9.4 9.39
2014.01.02 09:30:02.000 9.4 111300 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:05.000 9.4 185400 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:09.000 9.4 10500 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:15.000 9.4 200 9.39 9.38 9.37 9.36 9.35
q)select bPrc: bPrc1[0] from tb
bPrc
9.43
9.42
9.41
9.4
9.39
^^^^^^^
That is probably not what I want.
q)(flip tb[`bPrc1])[0]
9.43 9.39 9.39 9.39 9.39 9.37 9.37 9.37 9.38 9.38 9.38 9.38 9.38 9.38 9.37 9…
The only method I can think of is, flip the entire list, and put it back.
could anyone suggest a better method?
Thanks
Gary
0925fd46-5d6a-4394-955f-9cefd96d38d8@googlegroups.com>To: Gary Chow , Kdb+ Personal Developers
Try either:
select bPrc1[;0] from tb
select first each bPrc1 from tb
Or if you want a list not a table, use exec as Attila suggested.
David
From: Gary Chow
Sent: Friday, March 11, 2016 03:06
To: Kdb+ Personal Developers
Reply To: personal-kdbplus@googlegroups.com
Subject: [personal kdb+] selecting single element from a list
|
Hi,
I wonder if there is a way to select a single element from a list, for example...
date time prc vol bPrc1
-------------------------------------------------------------
2014.01.02 09:25:05.000 9.44 1461700 9.43 9.42 9.41 9.4 9.39
2014.01.02 09:30:02.000 9.4 111300 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:05.000 9.4 185400 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:09.000 9.4 10500 9.39 9.38 9.37 9.36 9.35
2014.01.02 09:30:15.000 9.4 200 9.39 9.38 9.37 9.36 9.35
q)select bPrc: bPrc1[0] from tb
bPrc
----
9.43
9.42
9.41
9.4
9.39
^^^^^^^
That is probably not what I want.
q)(flip tb[`bPrc1])[0]
9.43 9.39 9.39 9.39 9.39 9.37 9.37 9.37 9.38 9.38 9.38 9.38 9.38 9.38 9.37 9...
The only method I can think of is, flip the entire list, and put it back.
could anyone suggest a better method?
Thanks
Gary
--
Submitted via Google Groups
Thanks David and Attila,
I think bPrc1[;0] sounds more intuitive for me. And it actually remind me that in this case, bPrc1 is a 2D array.
Gary