Searchsorted by=<transform> keyword question

General Usage
1

I thought that the transform specified with the by keyword was a function applied before the comparison. I don’t understand the last three examples below. Probably missing something obvious.

How does the by keyword work?

These make sense

julia> searchsorted([11,12,13,14,15],1)
1:0

julia> searchsorted([11,12,13,14,15],100)
6:5

julia> searchsorted([11,12,13,14,15],13)
3:3

julia> searchsorted([-15,-14,-13,-12,-11], 13)
6:5

julia> searchsorted([-11,-12,-13,-14,-15], 13, by=abs)
3:3

julia> searchsorted([-11,-12,-13,-14,-15], 13, by=x->abs(x))
3:3

What is wrong here?

julia> searchsorted([11,12,13,14,15],13, by= x->x^2) # should be 1:0 ?
3:3

julia> searchsorted([11,12,13,14,15],13, by= x->x+100) # should be 1:0 ?
3:3

julia> searchsorted([11,12,13,14,15],130, by= x->x+100) # should be 3:3 ?
6:5
2

The function by is applied to both sides of the comparison, as in by(x) < by(y), so those results all look correct to me.

1 Like
3

That makes sense. Thank You!