Conditionally Format Bar Chart

Is it possible to create a conditionally formatted bar chart?

I have a time series bar chart that has positive and negative values, I would like to color code the bars based on a binary signal?

I have an example of the graph here http://www.mediafire.com/i/?f3yow24335ictbn

[Thomas]

On what condition are the bars blue or red?

[luke]

I have a signal that is a 1 or -1 for each day

Answer 1

[Matt Tearle]

Not sure if I understand your comment exactly, but it sounds like you have x & y data, then another variable z(x) that is +1 or -1, and you want to color the (x,y) plot according to the value of z. If so:

% some fake data
x = 1:20;
y = randi(100,size(x))-50;
% signal of -1 or +1
z = randi([-1,1],size(x));;

% find the values where z = -1
idx = (z==-1);
% plot them
bar(x(idx),y(idx),'r')
hold on
% now the others (z = +1)
bar(x(~idx),y(~idx),'b')
set(gca,'XTickMode','auto')
hold off

The bar function messes with the axis ticks, hence the set command at the end. You could also specify the tick values manually:

set(gca,'XTick',x)

Answer 2

[Thomas]

Don't know if there is an easier way, this is not too bad.. This gives lines like the example image..

clear all
close all
clc
 c=(randn(10,1));
f=randi([-1 1],1,10);
f(f==0)=1;
f=f';

q=[f c]   % this is your input with col 1 val -1 or 1, col 2 actual value

for i=1:length(q)
if q(i,1)==-1

line([i i],[0,q(i,2)],'Color','r')
hold on
else

line([i i],[0,q(i,2)],'Color','b')
hold on
end
end

line([0 length(q)],[0 0],'Color','k')

or try : this give bars

clear all
close all
clc
 c=(randn(10,1));
f=randi([-1 1],1,10);
f(f==0)=1;
f=f';

q=[f c]   % this is your input with col 1 val -1 or 1, col 2 actual value
val=(q(:,1)==1);
d=[1:length(q)];
bar(d(val),q(val,2),'r','LineWidth',1)
hold on
bar(d(~val),q(~val,2),'b','LineWidth',1)