RE: Pattern Matching in Lists
- To: mathgroup at smc.vnet.net
- Subject: [mg35563] RE: [mg35547] Pattern Matching in Lists
- From: "David Park" <djmp at earthlink.net>
- Date: Fri, 19 Jul 2002 06:08:18 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Anthony,
Here are three ways.
w = {1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0};
w2 = Partition[w, 2, 1];
Count[w2, {1, 0}]
4
count = 0;
Do[If[w[[i]] == 1 && w[[i + 1]] == 0, count++],
{i, 1, Length[w] - 1}];
count
4
Count[Drop[w - RotateLeft[w], -1], 1]
4
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Anthony Mendes [mailto:amendes at zeno.ucsd.edu]
To: mathgroup at smc.vnet.net
Hello,
Suppose w={1,1,1,0,0,1,0,1,0,0,1,0,0}.
How can I count the number of occurrences of a 1 in w immediately
followed by a 0 in w?
I have tried every incarnation of Count[] I can think of; for example,
Count[w,{___,1,0,___}]
does not seem to work. In general, how can I count the number of
occurrences of a 1 followed by a 0 in a list of 1's and 0's? Thank you!
--
Tony
_____________________
amendes at math.ucsd.edu