Plot selected variables according to flag
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I have three variables
x1, x2 and x3
and vector, say,
flag = [1 0 1]
If I want to plot on the same figure x1, x2 and x3, but only if flag(i) == 1, how can I do it without using if-else and switch-case?
I'm looking for a more compact way of writing:
figure; hold on;
if (flag(1))
plot(x1)
elseif (flag(2))
plot(x2)
elseif (flag(3))
plot(x3)
end
Also, how do I add a legend to the plot, that changes with the number of variables plotted?
1 个评论
Stephen23
2017-5-5
Creating lots of separate variables will make your code more complex than it needs to be. When you put all of your data together into one array (numeric, cell, struct, table,...) then accessing it is trivial using indexing or fieldnames.
采纳的回答
"I have three variables x1, x2 and x3..."
And there's the crux of the problem--do NOT create sequentially-name variables in Matlab; use arrays instead--
x=[x1 x2 x3]; % put the data together
flag=logical([1 0 1]); % the addressing logical array...
plot(x(flag,:)) % and plot those wanted
Above does assume each has same number of elements so can concatenate into double array; if they're of disparate lengths then either pad shorter with NaN to length of longest or can do similar addressing with cell arrays where each cell contains one of the arrays. But, "keep it simple" is the first rule until reach a real need for more complex solutions.
ADDENDUM
Well, as noted in the comment, using a state variable array solution is the most concise.
The next level of complexity that gives you most of what you're looking for would be a structure with named fields that match up to what your variable names are.
There, you can then refer to names dynamically as in
>> s=struct('position',1,'velocity',2,'accel',3)
s =
position: 1
velocity: 2
accel: 3
>> s.velocity % address single field
ans =
2
>> names=fieldnames(s) % can get fieldnames dynamically...
names =
'position'
'velocity'
'accel'
>> flag=logical([1 0 1]); % the logical vector again...
>> for i=names(flag).' % address those dynamically
s.(char(i))
end
ans =
1
ans =
3
>> s.accel=linspace(0,1,3) % fields can hold vectors, other
s =
position: 1
velocity: 2
accel: [0 0.5000 1]
>>
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