Plot data in loop with num2str

Hi all,

I want to plot a dynamic figure by plotting the sixth column of the datasets Meteo1752 to Meteo1966:

balyr=1752;
endyr=1966;
for k = balyr:endyr
  balanceyear(k-balyr+1,:)=k;
  plot(['Meteo' num2str(k) '(:,6)']);
end

However, the error says

Error using plot
Invalid first data argument.

What am I doing wrong?

Thanks

[Adam]

doc plot

tells you what the valid data types are for the inputs. plot expects numeric data arguments (or an axes handle as first argument). You are giving it a string.

You'll have to give your actual data to the plot instruction, and probably you will need to use

doc hold

too.

[Stephen23]

@yoni verhaegen: what you are trying to do is not recommended. Read this to know why:

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

It is easy to avoid this situation: usually some indexing is the key.

Answer 1

[Dimitris Kalogiros]

If you want to display something on your workspace, use disp() instead of plot()

balyr=1752;
endyr=1966;
for k = balyr:endyr
  balanceyear(k-balyr+1,:)=k;
  %plot(['Meteo' num2str(k) '(:,6)']);
  disp(['Meteo' num2str(k) '(:,6)']);
end

Answer 2

[dpb]

Several things...the specific error is trying to plot() a string; ML will not do character substitution like that.

The more fundamental issue is in having created the multiple variables with sequential names; as you've just discovered, now you have a problem in addressing them.

See the FAQ that talks about how to avoid the problem; we don't know how these were created so the best way to choose isn't clear.