MATLAB:确定一个值是否在向量中连续重复 N 次 [英] MATLAB: Identify if a value is repeated sequentially N times in a vector
问题描述
我试图确定一个值是否在向量中按顺序重复 N 次.我面临的挑战是它可以在向量内连续重复 N 次.目的是确定某行中某个值有多少次低于平均值.例如:
I am trying to identify if a value is repeated sequentially in a vector N times. The challenge I am facing is that it could be repeated sequentially N times several times within the vector. The purpose is to determine how many times in a row certain values fall above the mean value. For example:
>> return_deltas
return_deltas =
7.49828129642663
11.5098198572327
15.1776644881294
11.256677995536
6.22315734182976
8.75582103474613
21.0488849115947
26.132605745393
27.0507649089989
...
(例如，我只打印了几个值，但向量很大.)
(I only printed a few values for example but the vector is large.)
>> mean(return_deltas)
ans =
10.50007490258002
>> sum(return_deltas > mean(return_deltas))
ans =
50
因此 return_deltas 中有 50 个值的实例大于 return_deltas 的平均值.
So there are 50 instances of a value in return_deltas being greater than the mean of return_deltas.
我需要确定 return_deltas 中的值连续 3 次大于其平均值的次数.换句话说，如果 return_deltas 中的值连续 3 次大于其平均值，那就是一个实例.
I need to identify the number of times, sequentially, the value in return_deltas is greater than its mean 3 times in a row. In other words, if the values in return_deltas are greater than its mean 3 times in a row, that is one instance.
例如:
---------------------------------------------------------------------
| `return_delta` value | mean | greater or less | sequence |
|--------------------------------------------------------------------
| 7.49828129642663 |10.500074902 | LT | 1 |
| 11.5098198572327 |10.500074902 | GT | 1 |
| 15.1776644881294 |10.500074902 | GT | 2 |
| 11.256677995536 |10.500074902 | GT | 3 * |
| 6.22315734182976 |10.500074902 | LT | 1 |
| 8.75582103474613 |10.500074902 | LT | 2 |
| 21.0488849115947 |10.500074902 | GT | 1 |
| 26.132605745393 |10.500074902 | GT | 2 |
| 27.0507649089989 |10.500074902 | GT | 3 * |
---------------------------------------------------------------------
星号代表连续 3 个成功的序列.这个集合的结果是两次，因为有两次值连续大于平均值 3 次.
The star represents a successful sequence of 3 in a row. The result of this set would be two because there were two occasions where the value was greater than the mean 3 times in a row.
我的想法是创建一个新的向量:
What I am thinking is to create a new vector:
>> a = return_deltas > mean(return_deltas)
当然包含 return_deltas 中的值大于均值的那些，并使用它来查找顺序中 return_deltas 中的值大于其均值的次数连续3次.我正在尝试使用内置函数(如果有，我还没有发现它)或至少避免循环来做到这一点.
that of course contains ones where values in return_deltas is greater than the mean and using it to find how many times sequentially, the value in return_deltas is greater than its mean 3 times in a row. I am attempting to do this with a built in function (if there is one, I have not discovered it) or at least avoiding loops.
对我的处理方式有什么想法吗?
Any thoughts on how I might approach?
推荐答案
通过一点点工作，这个代码段找到了每组数字的起始索引:
With a little work, this snippet finds the starting index of every run of numbers:
[0 find(diff(v) ~= 0)] + 1
一个例子:
>> v = [3 3 3 4 4 4 1 2 9 9 9 9 9]; # vector of integers
>> run_starts = [0 find(diff(v) ~= 0)] + 1 # may be better to diff(v) < EPSILON, for floating-point
run_starts =
1 4 7 8 9
求每次运行的长度
>> run_lengths = [diff(run_starts), length(v) - run_starts(end) + 1]
这个变量可以很容易地查询哪些运行超过了特定数量
This variables then makes it easy to query which runs were above a certain number
>> find(run_lengths >= 4)
ans =
5
>> find(run_lengths >= 2)
ans =
1 2 5
这告诉我们，连续运行至少四个整数的唯一运行是运行 #5.
但是，有 3 次运行至少连续两个整数，特别是运行 #1、#2 和 #5.您可以从 run_starts 变量中引用每次运行的开始位置.
This tells us that the only run of at least four integers in a row was run #5.
However, there were three runs that were at least two integers in a row, specifically runs #1, #2, and #5.
You can reference where each run starts from the run_starts variable.
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