matrix creation from a loop

Hello all,

I would like to create 60 vector columns of zeros (6964,1) called lat_01_days, lat_02days, lat_03_days until 60. I know I could write them one by one but if i know How to create a loop to create them it would be better also for future research. Can someone help mep lease?

regards

Jonathan

[Stephen23]

"I would like to create 60 vector columns of zeros (6964,1) called lat_01_days, lat_02days, lat_03_days until 60."

Numbering variables like that is a sign that you are doing something wrong.

Forcing meta-data (e.g. pseudo-indices) intoe variable names is a sign that you are doing something wrong.

"I know I could write them one by one ..."

Ouch!

"...but if i know How to create a loop to create them it would be better also for future research"

In fact what "would be better also for future research" is to avoid numbered variables entirely:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Jonathan Demmer]

Thank you very much.

Answer 1

[Walter Roberson]

if i know How to create a loop to create them it would be better also for future research.

Our long experience is that it would make your future research worse instead of better.

http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

[Jonathan Demmer]

Thank you very much

Answer 2

[Stephen23]

The simplest and most efficient solution is to just create one matrix:

lat = zeros(6964,60)

which you can then trivially access using indexing. There is no point in making it more complex than that.

Answer 3

[Ruger28]

The two other answers are a more correct way of doing it. There is no need to create this many variables in your workspace. However, if you must...

You should use a structure instead of individual variables.

Blank_Vec = zeros(6964,1);
Num_Cols = 60;

for ii = 1:Num_Cols
    name = sprintf('lat_%i_days',ii);
    ZeroColStruct.(name) = Blank_Vec;
end

if you absolutely MUST have individual variables, one method is this:

% Removed due to being a terrible way to do something

[Stephen23]

Do NOT follow this advice. It teaches a complex and inefficient use of MATLAB.

"However, if you must..."

"if you absolutely MUST have individual variables..."

Most of the situations that I have read on this forum where someone explains why they "must" use dynamic variable names it turns out to be simpler and more efficient to solve using other approaches. A not-very-well-informed-user's idea of "must" is unlikely to be very correct, based on many years of threads on this forum.

For basic tasks like the one shown in this question, I have yet to see any situation that is not better solved using the recommended approach of basic MATLAB indexing.

[Jonathan Demmer]

I am kind of new i understand what everybody else is saying above and i will follow your guidelines. Thank you very much.

[Jonathan Demmer]

Thank you Stephen for your advice.