Length of monotonic sequencies
- To: mathgroup at smc.vnet.net
- Subject: [mg33579] Length of monotonic sequencies
- From: merkat <cabanc at hotmail.com>
- Date: Mon, 1 Apr 2002 02:02:13 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hi
I want to get the lengths of the monotonic rising and falling parts
in a list l.
for this I can use:
Drop[RotateRight[l] - l, 1];
% /. x_ /; x > 0 -> 1 ;
% /. x_ /; x < 0 -> -1 ;
Split[%]
Length /@ %
I want to include the case of no change in the sequence values which
makes the seqence longer. (flat progression)
I further want to relax the condition of monotonicity by allowing
shallow drops in the sequences.
for a drop of one unit:
{ 2,3,2,3,4,3,5,3,4,3,7} gives {7,4}
for a drop of 2 units:
{2,3,4,2,5,6,5,1} gives {7,1}
how can the code be written for an arbitrary drop?
Merkat