Select variables for plot

Hello

I have a vector and a matrix obtained from another function, but the structure is like the vector

and matrix inside 'callplot'.

The code, is just like this. I really dont know how to write in the right way this

pl(1:2)='t1,y1(:,1)'

inside the if function.

function f=callplot
t1=[0;1;2;3;4;5];
y1=[1 2 3 4; 5 6 7 8; 9 10 11 12; 13 14 15 16; 17 18 19 20; 21 22 23 24];
in1=0; in2=0; in3=0; in4=0;
a=0; b=0; c=0;

while in1~='Y'||'N';  
in1=input('¿You want to plot the variable X? (Y/N)','s');
if in1=='Y' pl(1:2)='t1,y1(:,1)'; elseif in1=='N' a=1; end
end

while in2~='Y'||'N';  
in2=input('¿You want to plot the variable R? (Y/N)','s');
if in2=='Y' pl(3-2*a:4-2*a)='t1,y1(:,2)'; elseif in2=='N' b=1; end
end

while in3~='Y'||'N';  
in3=input('¿You want to plot the variable N? (Y/N)','s');
if in3=='Y' pl(5-2*(a+b):6-2*(a+b))='t1,y1(:,2)'; elseif in3=='N' c=1; end
end

while in4~='Y'||'N';  
in4=input('¿You want to plot the variable Z? (Y/N)','s');
if in4=='Y' pl(7-2*(a+b+c):8-2*(a+b+c))='t1,y1(:,2)'; end
end

plot(pl)
%If all variables are selected to be plotted
%It should do the same as this
%plot(t1,y1(:,1),t1,y1(:,2),t1,y1(:,3),t1,y1(:,4))
%but obviously, I want pl can have any structure posible
%according to the user plot choices.
end

The error displayed when I Input Y is:

 ??? Subscripted assignment dimension mismatch.

 Error in ==> callplot at 9 if in1=='Y' pl(1:2)='t1,y1(:,1)'; elseif in1=='N' a=1; end

Additionally, it looks like the elseif isn't working either. When I Input N, it just display the

prompt again (It should only happen when input is different from Y or N). I suspect my error is on the ~='Y'||'N'

I hope to be clear enough, sorry if my english is not good.

Answer 1

[Aaditya Kalsi]

The short answer is writing code like this is bad practice when it comes to changing it later and may bring many other problems. The other short answer is EVAL. You can use something like:

eval(['plot(' pl ');']);

The better way to do this:

% if you must use input
answersGiven = {in1; in2; in3; in4; in5};
% gets the columns to be selected
boolCols = strcmpi('y', answersGiven);
% converts logical into column numbers
colNums = find(boolCols == true);
% plot(t1, y1(:, colNums));

This should do it. I didn't have MATLAB open so the code may gve errors! Sorry about that. But the idea should be pretty clear.

[Jose]

I like your way, I'll try that the next time.

Answer 2

[Walter Roberson]

while in1~='Y'||'N';

is interpreted as

while (in1~='Y') || 'N';

which is

while (in1~='Y') || ('N' ~= 0)

Now as 'N' is not 0, the statement is always true.

You want an "and" instead of an "or"

while in1~='Y' && in1 ~='N';

What do you want

pl(1:2)='t1,y1(:,1)'

to mean?

[Jose]

Thx, i really figured out how to do it yesterday, just like you said.

About the pl(1:2)='t1,y1(:,1)', I found the right way to do it, it was

plt=t1; ply(:,1)=y1(:,1)

So when i get all the columns selected for ply, I simply use plot(plt,ply).