Decimate every row in a matrix

Question

Edward Keavney 2022-9-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1804945-decimate-every-row-in-a-matrix

回答： Chunru 2022-9-14

Hi,

I have an array 26X10600 and have successfully managed to decimate the data to the required factor, however the decimate function only applies this to the first row in the array.

Is there a way to apply the decimate function to all the rows in the array? Perhaps using a loop?

Thanks in advance,

Ed.

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Answer 1

Chunru 2022-9-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1804945-decimate-every-row-in-a-matrix#answer_1053165

在 MATLAB Online 中打开

% assume that decimate is used for downsampling
a = randn(100, 26);         % time is along the column
[ns, nch] = size(a);
r = 5;
ns_down = floor(ns/r);
a_down = zeros(ns_down, nch);
for i=1:nch
    a_down(:, i) = decimate(a(:, i), r);
end
% if you use resample
a_down = resample(a, 1, 5)
a_down = 20×26
    0.2035    0.5894    0.4277    0.5124   -0.2946    0.0375   -0.4256    0.5500   -0.0988   -0.3491   -0.2059   -0.1932   -0.0076    0.1527   -0.1606   -0.4525   -0.2297   -0.3152    0.3082   -0.1657    0.0273    0.6115   -0.1139   -0.2836   -0.0841   -0.4076
    0.0088    0.7556   -0.3695    0.3144    0.2809    0.0622    0.2201    0.4081   -0.4480    0.1609    0.3844    0.0006    0.2010    0.6847   -0.6279   -0.6199   -0.5940   -0.5327   -0.1417   -0.5802    0.0935    0.1891    0.3220    0.2975    0.1581   -0.7951
    0.7662    0.1463    0.0618   -0.1744   -0.5694   -0.6003   -0.2815    0.2072    0.0655   -0.0817    0.4674   -0.2274    0.5296   -0.3111   -0.2398   -0.5233    0.1860    0.3026   -0.3302   -0.1080   -0.0559    0.4351   -0.0301    0.5064    0.7205    0.5174
   -0.0342    0.8585    0.1987    0.0411   -0.0507    0.0990   -0.1219   -0.0178    0.3059    0.3170   -0.1951   -0.7662   -0.2090    0.0570    0.2217   -0.8785    0.2394    0.2453    0.6089   -0.5470   -0.0330    0.4841    0.2075   -0.0729   -0.1621   -0.3895
   -0.8904   -0.3186   -0.0481   -0.3479   -0.1071   -0.0601    0.3548   -0.4403    0.2610    0.1760    0.7389    0.3950   -0.0848   -0.4017    0.4266   -0.3536   -0.3203   -0.6671   -0.0697   -0.5183   -0.3654   -0.0970    0.4209    0.6660    0.3831    0.0612
   -0.3664    0.0807   -0.4412    0.3605    0.7926    0.4394    0.6065   -0.7204    0.2546   -0.3633   -0.5788   -0.5178   -0.5565   -0.1363    0.6631   -0.3883   -0.0159   -0.8875   -0.2291   -0.1563   -0.7098    0.5201   -0.0395    0.8904    0.4703    0.3960
    0.2005    0.0582   -0.6620    0.5480    0.5580    0.2919    0.5541    0.3168   -0.9495   -0.8333   -0.7845   -0.1338    0.4028    0.5476    0.1172   -0.9842    0.1029    0.0986   -0.1060   -0.3599    0.6724   -0.1903    0.7076    0.2337   -0.0446   -0.1107
   -0.2820    0.1991   -0.1359   -0.2455   -0.9743   -0.0588    0.2309    0.8561    0.0654   -0.5078    0.3556    0.1620    0.4531    0.3374    0.2375   -0.5716    0.5632   -0.4275   -0.1056   -0.1951    0.2659   -1.0951    0.4419   -0.4905    0.3387    0.1454
    0.7738    0.5488   -0.1856    0.9091   -0.2801   -0.5387   -0.1921   -0.1776    0.1818    0.0328    0.4397    0.5422   -0.3121   -0.1097   -0.4251   -1.4804   -0.0117    0.2012    0.3562   -0.7029    0.4486    0.3344   -0.4861    0.0063   -0.7187   -0.3091
    0.7240    0.6699    0.3239   -0.1987   -0.6077   -0.2540    0.2003    0.8084    0.7762   -0.2350    0.0293    0.4720    0.3072    0.1202    0.1659   -0.1834   -0.0185   -0.2352   -0.7081   -0.2282   -0.3236    0.4145   -0.1915    0.1940    0.2924   -0.2986