save two variables using num2str

I want to save two variables using num2str, but I get error. what is wrong with this?

x1=1;
y1=2;
ty_c=1;
pathdatasave = (['D:\testa\ty' num2str(ty_c) '\']); 
save([pathdatasave 'test_x' num2str(x1) '_y' num2str(y1)  '.mat'],['varx'  num2str(x1) ,'vary' num2str(y1)]);

[Stephen23]

"what is wrong with this?"

Forcing meta-data (e.g. pseudo-indices) into variable names is a sign of poor data design, which when you try to access your data forces you into writing slow, complex, inefficient, obfuscated, insecure, buggy code which is hard to debug (your code).

[Ham Man]

I separated varx vary by individual brackets and it works fine:

save([pathdatasave 'test_x' num2str(x1) '_y' num2str(y1) '.mat'],['varx' num2str(x1)] ,['vary' num2str(y1)]);

[Ham Man]

Thanks for the time

[Stephen23]

Context: https://www.mathworks.com/matlabcentral/answers/1756925-using-eval-with-save-function

Answer 1

[Stephen23]

"what is wrong with this?"

1. Forcing meta-data (pseudo-indices) into variable names, thus making your code slow and complex.
2. Forcing code into one line, when clarity is actually more important (as this question demonstrates).
3. Two variable names must be supplied as two inputs to SAVE (not concatenated together as you are doing):

x1=1;
y1=2;
varx1 = 33;
vary2 = 444;
P = '.';
F = fullfile(P,sprintf('test_x%d_y%d.mat',x1,y1));
N1 = sprintf('varx%d',x1);
N2 = sprintf('vary%d',y1);
save(F,N1,N2);
%      ^^ ^^ two variable names == two inputs, not one like you did!

Checking:

whos -file test_x1_y2.mat

  Name       Size            Bytes  Class     Attributes

  varx1      1x1                 8  double              
  vary2      1x1                 8  double              

So, everything works exactly as documented and expected.

[Ham Man]

Thank you