Adding Data to an Existing Nx1 Double

Hello everyone. I have a 257x1 double that I need to add zero values to at set locations without removing the pre-existing data, in essence expanding the double to a 264x1.

I've been searching through existing answers but am still not quite getting it due to most cases involving NxM matrices as opposed to having a single column.

Thanks for your help Conor

EDIT -------------- After some additional searching I found a method that solves my problem but I am still curious if it is the most efficient, here is my finished code:

    U = ones (264,1);
    U (:) = NaN;
    U ([9;37;38;39;49;50;51]) = 0;
    URLocations = find (isnan (U));
    U (URLocations) = UR;

Answer 1

[Stephen23]

Simplified a little:

U = nan(264,1);
U([9;37;38;39;49;50;51]) = 0;
U(isnan(U)) = UR;

• find is not required and is just slows the code down. Logical indexing is faster.
• there is no point creating a matrix of ones when you want a matrix of NaNs.
• allocating the index variable just clutters the workspace and slows the code.

An alternative ( I have no idea if this will be faster, you should time them with timeit ):

U = zeros(264,1);
U(setdiff(1:264,[9;37;38;39;49;50;51]) = UR;

[Conor J Crickmore]

Thank you very much, explains why you did what you did too :-)