Function - Input is a numeric vector x (any length). Return value is a list of string and matlab

Hi Matlab Community

I'm new to programming and I'm learning Matlab.

I'm trying to figure out this problem.

I need to create a function where the input is a numeric vector x (any length). Return value is a list of string.

If the x <= 30, then return “small”, if 30 < x <= 50, then return “medium”, otherwise return “high”

When I run the function I get vec = Small

Here is the function:

function x = numvec(v)
%x = []
for i =length(v);
    if v(i) <= 30;
        x = 'small';
    elseif (30 < v(i)) & (v(i) <=50)
        x = 'medium';
    end
end

When I call the function.

v = [30, 25, 66, 10, 5]

vec = numvec(v)

OUTPUT:

vec =

    'small'

Your input is greatly appreciated.

Thanks!!

Answer 1

[Walter Roberson]

You are overwriting all of x on each iteration. You need to write to x(i) instead of to x

Also, for i =length(v) only uses length(v) exactly, and not 1, 2, 3, and so on. You need 1:length(v)

Thirdly, for this particular purpose, you need to use " instead of ' -- so "small" instead of 'small' . 'small' is a character vector, a 1 x 5 array of char, rather than being a string() object, but "small" is a 1 x 1 string object.

[Steven Lord]

You may also want to preallocate x to be a string array of the same size as v before you start looping over the elements in v, so that you're replacing an existing element in x rather than growing x at each iteration.

x = repmat("high", size(v)); % Choosing one of the possible values arbitrarily

[Emmanuel Matata Bili Bili]

I implemented both solutions and it worked perfectly.

Thanks for the clarification, Walter and Steven!!!