在数组中查找序列数 [英] Finding the # of sequences in an array

问题描述

我需要报告数组中的序列数.例如:

I need to report the # of sequences in an array. For example:

A=[ 1 1 -1 -1 -1 -1 -1 0 1 -1 -1 -1 -1 1 1 -1 -1 1 0 1 1]

而且我必须报告一个数字连续出现的次数，例如

and I have to report the # of times a number comes consecutively, such as, one sequence of

5 -1s ([-1 -1 -1 -1 -1])和一个序列

4 -1s ([-1 -1 -1 -1]).

如何查找有多少个数字序列?

How can I find how many sequences of numbers there are?

推荐答案

您可以使用游程长度编码以执行此任务

You may use run-length encoding to perform this task

function [rl data] = runLength( vec )
% run length encoding for vector vec
rl = ( find( vec ~= [vec(2:end), vec(end)+1] ) );
data = vec( rl );
rl(2:end) = rl(2:end) - rl(1:end-1);

将游程长度编码应用于A

Applying run-length encoding to A

>> [rl data] = runLength( A )
rl =
   [ 2 5 1 1 4 2 2 1 1 2 ]
data =
   [ 1 -1 0 1 -1 1 -1 1 0 1 ]

因此，如果您对长度为n的序列数感兴趣，那么您需要的是

So, if you are interested in the number of sequences of length > n all you need is

>> nnz( rl > n )

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