How to repeat the first number only

Array a is given

a =[1]

How can I add 0 to the array depending on n.

n=1 --> a=[0 1]
n=2 --> a=[0 0 1]
n=3 --> a=[0 0 0 1]
and n can be changes to any number

Answer 1

[madhan ravi]

a = 1;
n = 2;    % just an example n
a = [zeros(1,n) a]

[fyza affandi]

Thank you very much :)

[madhan ravi]

Anytime :) , respond to your previous question https://in.mathworks.com/matlabcentral/answers/434359-how-to-add-1-into-the-array#answer_350993

Answer 2

[Image Analyst]

madhan's way is the best (how I'd do it), but I just want to show you a neat trick - that you can "grow" an array by simply assigning something to the last location (the location at the largest point that you want to grow it to):

a = 1; % Initial array.
n = 2;    % just an example n
% a = [zeros(1,n) a]  % Best way
a(n+1) = 0; % Enlarge array by appending zeros simply by assigning the last element.
a = fliplr(a) % Flipr it so that the 1 is on the right.

[madhan ravi]

+1 shows many ways :-)

[fyza affandi]

Thank you very much

[Image Analyst]

Glad you like it. Thanks for the vote. In that spirit, here is another one-liner way of doing it if you have the Image Processing Toolbox:

a = padarray(a, [0, n], 'pre')

It basically prepends n zeros to the beginning of array a.

[Stephen23]

Not just a neat trick, until R2015b allocating to the last element (and implicitly filling array with zeros) was faster than calling zeros:

https://www.mathworks.com/matlabcentral/answers/82989-fastest-way-to-fill-in-an-array#comment_161435

http://undocumentedmatlab.com/blog/preallocation-performance/

[Stephan]

49996 +2