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') I ask basically the same questions below, but in perhaps a more confusing or verbose way. ~~~ Two problems: How to plot multiple things without manually typing: PLOT(X1,Y1,S1,X2,Y2,S2,X3,Y3,S3,...) How to create a legend for multiple things without manually typing: LEGEND(string1,string2,string3, ...) I'm trying to plot six things and describe each uniquely, but possibly more than six (I'm trying to write the code so it's flexible, should someone want to use it to plot twenty things, for example). I thought I could simply repeat the plot and legend command within a for loop and it would automatically know what I'm trying to do, but it seems that doesn't happen (the lines are all the same color and the legend command overwrites the previous legend with each execution): 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') It would be great to be able to plot the lines distinctly, e.g. long and short dashes, solid, dotted, etc, and it might be necessary, but I think the minimum is to use colored lines (the MATLAB default). I see that one would use PLOT(X,Y,S) in the case of individual plots, but I don't know whether the syntax changes if trying to do what I'm describing here. So is it even possible? Or is there no way around it? I've tried the following (although not very useful since I don't know how to tell it to omit the final comma after the last pair), which fails as shown (and as expected): 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)?
Prashant Kumar answered .
2025-11-20
in = {1:10, 11:20, '.',3:4,2:3,'*'};
plot(in{:})
Question 2
str = {'A','B'};
legend(str{:})
{sk_ratio01, sk_ratio02;
fitco_1_01, fitco_1_02;
fitco_2_01, fitco_2_02;
'Co-60' , 'MV 4';
'*' , '+'}
s.('sk_ratio01') = struct('data',data,'fit1',fit1,'fit2',fit2,'marker','*','lbl','Co-60');
s.('sk_ratio02') = struct('data',data,'fit1',fit1,'fit2',fit2,'marker','+','lbl','MV 4');
eval(['spectrum' spectrumname '.energy=' spectrumname])
could be rewritten with dynamic field indexing:
spectrum.(['spn' spectrumname]).energy = spectrumname;
Note that a fieldname cannot start with a number (same rule as for variables applies).