matrix creation from a loop

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Jonathan Demmer
Jonathan Demmer 2020-9-17
编辑： Ruger28 2020-9-17
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
  2 个评论
Stephen23
Stephen23 2020-9-17
"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

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回答（3 个）

Walter Roberson
Walter Roberson 2020-9-17
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
Stephen23
Stephen23 2020-9-17
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.
Ruger28
Ruger28 2020-9-17
编辑：Ruger28 2020-9-17
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
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Jonathan Demmer
Jonathan Demmer 2020-9-17
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
Jonathan Demmer 2020-9-17
Thank you Stephen for your advice.

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