Re: Delete elements from list..
- To: mathgroup at smc.vnet.net
- Subject: [mg116653] Re: Delete elements from list..
- From: Achilleas Lazarides <achilleas.lazarides at gmx.com>
- Date: Wed, 23 Feb 2011 05:22:19 -0500 (EST)
Do you really want the resulting list to only have increasing elements? then something like
Module[{tmpl = mylist[[1]]},
Scan[(If[# > tmpl, Sow[#]; tmpl = #]) &,
mylist]; // Reap]
should work (except that it eats the first element).
If you actually meant that you want to delete any element that is not strictly larger than the previous, then
Module[{tmpl = mylist[[1]]},
Scan[(If[# > tmpl, Sow[#]]; tmpl = #) &,
mylist]; // Reap]
(which again eats the first element).
On Feb22, 2011, at 1:30 AM, Maarten van der Burgt wrote:
> Hallo,
>
> I have a list like:
>
> mylist = {1, 2, 3, 4, 5, 6, 4, 5, 7, 8, 9}
>
> I want to delete any element which is not strictly larger than the
> previous element, until my new list has only increasing values.
>
> This means in mylist above I want to delete the 4 and the 5 at position
> 7 and 8.
>
> Any elegant and fast way for doing this?
>
> In practice I want to do this for a large amount (1000) of very large
> lists (1000). So speed is important.
>
> Thanks for your help.
>
> Maarten