Decimate every row in a matrix

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.

Answer 1

[Chunru]

% 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