Plotting color data from cell array using plot()

I want to quickly plot several hundred traces quickly Using a for loop tends to take quite some time. I found a trick to do it using the following example,

x1 = [1 2 3]
x2 = [2 3 4]
y1 = [1 2 3]
y2 = [3 5 6]
xdata = {x1 x2}
ydata = {y1 y2}
plot(xdata{:}, ydata{:})

BUT

what if i want to color code the data in a specific way? I tried the following, but it doesnt work.

x1 = [1 2 3]
x2 = [2 3 4]
y1 = [1 2 3]
y2 = [3 5 6]
c1 = [1 0 1]
c2 = [0 1 0]
xdata = {x1 x2}
ydata = {y1 y2}
cdata = {c1 c2}
plot(xdata{:}, ydata{:}, 'color', cdata{:})

Is there any way to assign additional information to the information being plotted using plot() such as color, or line style? If not, is there another function? Or must a for loop be used for this

Answer 1

[Walter Roberson]

plot(xdata{:}, ydata{:})

is equivalent of

plot(xdata{1}, xdata{2}, ydata{1}, ydata{2})

which is going to treat the data as pairs and plot xdata{1} against xdata{2}, and plot ydata{1} against ydata{2}

To do it right you would need something like

xydata = [xdata; ydata];
plot(xydata{:})

Also

plot(xdata{:}, ydata{:}, 'color', cdata{:})

Would be treated as

plot(xdata{1}, xdata{2}, ydata{1}, ydata{2}, 'color', cdata{1}, cdata{2})

which would fail because cdata{2} is not the name of a valid named option.

Is there any way to assign additional information to the information being plotted using plot() such as color, or line style?

No. For any one plot() call, if you specify multiple name/value pairs with the same name, then it is the last pair that is used.

Although you could construct

cdata = [cellstr(repmat('color', length(xdata), 1)), {c1; c2}];
plot(xydata{:}, cdata{:})

to get the effect of

plot(xdata{1}, xdata{2}, ydata{1}, ydata{2}, 'color', c1, 'color', c2)

because of the rules around last-processed option, this would be equivalent to

plot(xdata{1}, xdata{2}, ydata{1}, ydata{2}, 'color', c2)

and the c1 color information would be ignored.

What you can do is

h = plot(xydata{:});
cdata = {c1 c2};
set(h, {'color'}, cdata(:))

This takes advantage of a special syntax of set(), that if you provide a cell array of a property name, then the property name will be effectively duplicated once for each handle and the corresponding cdata value will be used