How to downsample a vector x by an integer factor M with a single statement such as for loop or conditional statements

I have already learned to use downsample(）function. However, are there ways to use statements to downsample a vector?

Answer 1

[Chunru]

a = 1:10;
b = downsample(a, 3)        % use downsample

b = 1×4

1 4 7 10

c = a(1:3:end)              % statement

c = 1×4

1 4 7 10

[William]

Thank you for your answer! Could you please offer a solution with for loop or if statement？

[Chunru]

"for loop" is not as efficient as above. You should not use it.

a = 1:10;
j=1;
for i=1:3:length(a)
    b(j) = a(i); 
    j = j+1;
end
b

b = 1×4

1 4 7 10

[William]

Thank you so much!