Skip to main content
Mathematica

Return to Question

replaced http://mathematica.stackexchange.com/ with https://mathematica.stackexchange.com/
Source Link
Community Bot
Community Bot
  • 1

Searching by and I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns the closest number itself, not the position.

After some more looking around, I learned about MapIndexed and Rules, and came up with this:

NearestPosition[haystack_, needle_] := Nearest[haystack, needle] /. MapIndexed[Rule, haystack];

Is there a more efficient way, in general?

(And what if it's guaranteed the list comes sorted—can that be leveraged?)

The reason I'm concerned about efficiency is that I intend to use NearestPosition in a DynamicModule where it may be triggered by every mouseover event. (I'm still trying to solve this problemthis problem.)

Searching by and I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns the closest number itself, not the position.

After some more looking around, I learned about MapIndexed and Rules, and came up with this:

NearestPosition[haystack_, needle_] := Nearest[haystack, needle] /. MapIndexed[Rule, haystack];

Is there a more efficient way, in general?

(And what if it's guaranteed the list comes sorted—can that be leveraged?)

The reason I'm concerned about efficiency is that I intend to use NearestPosition in a DynamicModule where it may be triggered by every mouseover event. (I'm still trying to solve this problem.)

Searching by and I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns the closest number itself, not the position.

After some more looking around, I learned about MapIndexed and Rules, and came up with this:

NearestPosition[haystack_, needle_] := Nearest[haystack, needle] /. MapIndexed[Rule, haystack];

Is there a more efficient way, in general?

(And what if it's guaranteed the list comes sorted—can that be leveraged?)

The reason I'm concerned about efficiency is that I intend to use NearestPosition in a DynamicModule where it may be triggered by every mouseover event. (I'm still trying to solve this problem.)

Tweeted twitter.com/#!/StackMma/status/392902020786827264
Source Link
Andrew Cheong
Andrew Cheong
  • 3.7k
  • 19
  • 45

Efficiently searching a list for the position of the closest number to a specified number

Searching by and I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns the closest number itself, not the position.

After some more looking around, I learned about MapIndexed and Rules, and came up with this:

NearestPosition[haystack_, needle_] := Nearest[haystack, needle] /. MapIndexed[Rule, haystack];

Is there a more efficient way, in general?

(And what if it's guaranteed the list comes sorted—can that be leveraged?)

The reason I'm concerned about efficiency is that I intend to use NearestPosition in a DynamicModule where it may be triggered by every mouseover event. (I'm still trying to solve this problem.)