can some one please explain how scan works, when the left arg is a vector and the right arg is either atom or vector?
tia.
q)0 3 6 2 5 1 4[1] / / from idiom # 1005 of qidioms
1 3 2 6 4 5
)q 5 2 0 [1]
1 2 0 5 0N
q)4 6 1[1 2 3]
1 2 3
6 1
6
Just imagine the verb being indexing (@)
Cheers,
? Attila
so "" is used as iteration in this case, and as Attila said, the verb is indexing
iteration returns result as:
x,f(x),f(f(x)),f(f(f(x))),…
http://code.kx.com/wiki/Reference/BackSlash
so to explain the first question:
q)0 3 6 2 5 1 4[1]
1 3 2 6 4 5
the first result is 1, so return 1
use the first result and index ( (0 3 6 2 5 1 4)[1] ) which return 3
use the second result and index ( (0 3 6 2 5 1 4)[3] ) which return 2
use the third result and index ( (0 3 6 2 5 1 4)[2] ) which return 6
use the fourth result and index ( (0 3 6 2 5 1 4)[6] ) which return 4
use the fifth result and index ( (0 3 6 2 5 1 4)[4] ) which return 5
the result stops here because if you use the sixth result and index ( (0 3 6 2 5 1 4)[5] ) which return 1, the result (1 3 2 6 4 5) will just keep repeating itself indefinitely
so the best result q can return is 1 3 2 6 4 5 in the end…
if you use this logic on second and third question, it will be clearer
Thank you all, really appreciate it. Next time, I will read the documentation first.