Re: fastest way to find the first non-zero value in an array

smasson@[EMAIL PROTECTED]
 wrote:

> I want to find the first non-zero value of an array. Is there a faster
> way to do this than with the "where" command: (where(array ne 0))[0]
> "Where" will look for all non-zero values and I only need the first
> one. It would be great if I could stop "where" in its search process
> as soon as it found one element...

I agree.  You should submit a feature request so you can pass a keyword 
specifying FIRST or LAST and optionally the number of first or last 
elements you want returned.  Something like:

idx = WHERE(array ne 0, /FIRST)

Returns a scalar containing the index of the first non-zero element of 
array.


idx = WHERE(array ne 0, FIRST=10)

Returns a 10 element vector containing the first 10 indices where array 
is not equal to 0.


LAST would function in the same way except it would start from the end 
of the array and work backwards.

COMPLIMENT, and NCOMPLIMENT would function as they do now but of course 
COMPLIMENT would return indices for all elements in "array" beyond the 
point WHERE short-circuited.


-Rick