Calculate NN for only one vector

[kentkawai]

Hi,

In case I want to get NN for only one vector A1, "build" function needs to calculate NN for all vectors A1..n. But I don't need NN for vectors other than A1 vector, calculating NN for all other vectors is waste of time.
Are there any good way to calculate NN for only one vector?

[erikbern]

I don't understand... why don't you just compute the distance between A1 and all A2...An? You don't need Annoy to do this...

[kentkawai]

Ah, maybe I misunderstood. I thought ANN is the fast algorithm to get NN for one vector.
Thank you for your suggestion.

[erikbern]

That's O(n) so it's hard to optimize...