Oliviawilliams02 asked . 2020-09-01

How do we plot repetitive items simply? Can a loop and eval be used, for example? How d'you nest a string within a string?

Note the repetitive nature of the following script. Isn't it possible code this more simply using a loop of some kind, and perhaps the 'eval' command? Especially if you wanted to plot more than six items without changing the code? The 'co60', '4', '6','10','15', etc. correspond to the names of the data files (co60.dat, 4.dat, etc); I was able to create these vectors via the eval command. One difficulty I face is that I seem unable to nest strings within strings: For example, how do you specify 'o' when eval requires string inputs? How do you put a string within a string?

% This plots all 18 lines (3 per energy spectra) on one graph.
%figure
%  hold on
%  plot(depth,sk_ratio1,'.',depth,sk_ratio2,'o',depth,sk_ratio3,'x', ...
%       depth,sk_ratio4,'+',depth,sk_ratio5,'*',depth,sk_ratio6,'s')
%  plot(depth,fitco60_1_plot,'-',depth,fit4_1_plot,'-', ...
%       depth,fit6_1_plot,'-',   depth,fit10_1_plot,'-', ...
%       depth,fit15_1_plot,'-',  depth,fit24_1_plot,'-')
%  plot(depth,fitco60_2_plot,'--',depth,fit4_2_plot,'--', ...
%       depth,fit6_2_plot,'--',   depth,fit10_2_plot,'--', ...
%       depth,fit15_2_plot,'--',  depth,fit24_2_plot,'--')
%  title(['S/K vs Depth'])
%  xlabel(['Depth in cm'])
%  ylabel('Scerma to Kerma Ratio for Various Energy Spectra')
%  legend('Co-60','4 MV','6 MV','10 MV','15 MV','24 MV')

% This plots the lines for each energy spectra in its own graph in figure.
figure
 subplot(2,3,1)
  plot(depth,sk_ratio1,'.',depth,fitco60_1_plot,'-',depth,fitco60_2_plot,'--')
  xlabel('a')
  legend('Co-60','Linear fit','Quadratic fit')
 subplot(2,3,2)
  plot(depth,sk_ratio2,'o',depth,fit4_1_plot,'-',depth,fit4_2_plot,'--')
  xlabel('b')
  legend('4 MV','Linear fit','Quadratic fit')
 subplot(2,3,3)
  plot(depth,sk_ratio3,'x',depth,fit6_1_plot,'-',depth,fit6_2_plot,'--')
  xlabel('c')
  legend('6 MV','Linear fit','Quadratic fit')
 subplot(2,3,4)
  plot(depth,sk_ratio4,'+',depth,fit10_1_plot,'-',depth,fit10_2_plot,'--')
  xlabel('d')
  legend('10 MV','Linear fit','Quadratic fit')
 subplot(2,3,5)
  plot(depth,sk_ratio5,'*',depth,fit15_1_plot,'-',depth,fit15_2_plot,'--')
  xlabel('e')
  legend('15 MV','Linear fit','Quadratic fit')
 subplot(2,3,6)
  plot(depth,sk_ratio6,'s',depth,fit24_1_plot,'-',depth,fit24_2_plot,'--')
  xlabel('f')
  legend('24 MV','Linear fit','Quadratic fit')

1. How to plot multiple things without manually typing: PLOT(X1,Y1,S1,X2,Y2,S2,X3,Y3,S3,...)
2. How to create a legend for multiple things without manually typing: LEGEND(string1,string2,string3, ...)

figure
  hold on
for i = 1:numberofspectra
    spectrumname = input('Please input the spectrum''s file name: ','s');
 %  sk_ratio is calculated; by the way, the spectrum file ends in .dat

     eval(['sk_ratio' num2str(i) '= s_depth./k_depth;'])

      dotpos = find(spectrumname == '.', 1, 'last'); % from Walter Roberson
  if ~isempty(dotpos); spectrumname(dotpos:end) = []; end % Walter Roberson

        eval(['plot(depth,sk_ratio' num2str(i) ')'])
        legend(spectrumname)

end
  title(['S/K vs Depth'])
  xlabel(['Depth in cm'])
  ylabel('Scerma to Kerma Ratio for Various Energy Spectra')

      x1 = rand(1,3);
      y1 = rand(1,3);
      x2 = rand(1,3);
      y2 = rand(1,3);
      x3 = rand(1,3);
      y3 = rand(1,3);
      x4 = rand(1,3);
      y4 = rand(1,3);

figure
 plot( ...
for i = 1:3
    eval(['x' num2str(i) 'y' num2str(i) ','])
end
     x4,y4)
??? for i = 1:3
    |
Error: Illegal use of reserved keyword "for".

So how do you automate a multiple plot+legend, particularly with unique lines and well-placed legend (if possible)?

matlab , plot , plotting ,