MATLAB:比较2个具有不同长度的数组 [英] MATLAB: Comparing 2 arrays with different lengths

问题描述

我需要比较两个具有不同长度(由于采样率不同)的数组.我想对较大的数组进行下采样以匹配较小的数组，但是该因素不是整数而是十进制.

I have two arrays with different lengths (due to different sampling rates) that I need to compare. I'd like to downsample the larger array to match the smaller one in length, however the factor is not an integer but a decimal.

例如:

a =
     1     1.375     1.75     2.125     2.5     2.875     3.25

b =
     1     2     3

是否有任何方法可以操纵这些数组以匹配长度?

Is there any way to manipulate these arrays to match lengths?

推荐答案

聪明地使用 interp1 .诀窍在于，用于插值的关键点是一个数组，该数组从1到与a中的值一样多，我们将称为N，并且插值的关键点将是一个线性增加的数组，其中第一个点是1，最后一个点是N，您可以将此范围平均划分为与b中的点一样多.

That's easy to do with clever use of interp1. The trick is that the keypoints used for interpolation is an array going from 1 up to as many values as you have in a which we will call N, and the interpolated keypoints would be a linearly increasing array where the first point is 1, the last point is N and you evenly divide up this range to have as many points as there are in b.

简单地说:

anew = interp1(1:numel(a), a, linspace(1, N, numel(b)));

linspace 生成从1到N = numel(a)的点数尽可能多，我们将其确定为b中的元素总数.这恰好指定了您想要给与b的长度匹配的a的下采样版本的正确关键点，尽管将需要一些插值.默认的插值方法是线性.

linspace generates a linearly increasing array from 1 to N = numel(a) for as many points as you want, which we determine as the total number of elements in b. This exactly specifies the right keypoints you want to give you a downsampled version of a that matches the length of b, though there will be some interpolation required. The default interpolation method is linear.

使用您提供的a的示例输入，我们得到:

Using the sample input from a you provided, we get:

>> anew

anew =

    1.0000    2.1250    3.2500

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