I have a variable history that is filled like:
{{#1682051497} {emacsclient --create-frame org/dummy.org &}}
{{#1682051113} {time thinHistory.tcl}}
{{#1682051041} ll}
.
.
.

I use:
return [lsort -decreasing -index 0 ${history}]

to return it sorted decreasing on the first element of the containing
lists.
It seems that when the sort is not necessary that the sort does not
take much time. Can I count on this, or could it be that it is not
always the case and is it better to add code to make sure it is only
sorted when it is necessary?

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

* Cecil Westerhof <Cecil@decebal.nl>
| I use:
| return [lsort -decreasing -index 0 ${history}]
>
| to return it sorted decreasing on the first element of the containing
| lists.
| It seems that when the sort is not necessary that the sort does not
| take much time. Can I count on this, or could it be that it is not
| always the case and is it better to add code to make sure it is only
| sorted when it is necessary?

man lsort(n)
The implementation of the lsort command uses the merge-sort
algorithm which is a stable sort that has O(n log n) performance
characteristics.

I read that merge-sort on an almost sorted list has good performance.
So as long as the algorithm of lsort is not changed...

But.
How much time max is it allowed to take before sorting becomes
noticeable? 1 second? 1 millisecond?

A history list sounds useful only if it does *not* contain zillions of
entries, and for anything less than say some hundred entries the time
for sorting it once should not be noticeable.

R'

Ralf Fassel <ralfixx@gmx.de> writes:

> * Cecil Westerhof <Cecil@decebal.nl>
> | I use:
> | return [lsort -decreasing -index 0 ${history}]
>>
> | to return it sorted decreasing on the first element of the containing
> | lists.
> | It seems that when the sort is not necessary that the sort does not
> | take much time. Can I count on this, or could it be that it is not
> | always the case and is it better to add code to make sure it is only
> | sorted when it is necessary?
>
> man lsort(n)
> The implementation of the lsort command uses the merge-sort
> algorithm which is a stable sort that has O(n log n) performance
> characteristics.
>
> I read that merge-sort on an almost sorted list has good performance.
> So as long as the algorithm of lsort is not changed...

Well, when only one element was out of order, the program took about
three times as long to execute. But when none where out of order it
took about the same time with, or without sort.

> But.
> How much time max is it allowed to take before sorting becomes
> noticeable? 1 second? 1 millisecond?

In this case it is not something to worry about, but I like to learn
things I do not need right away. :-D

> A history list sounds useful only if it does *not* contain zillions of
> entries, and for anything less than say some hundred entries the time
> for sorting it once should not be noticeable.

The one I tested it on had about 150. I know that thousands are not
uncommon and that there are people who use tens of thousands.

Thanks. I keep it without extra code.

--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof