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BreakAxis

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30 Jun 2003 (Updated )

Produces a plot who's y-axis skips to avoid unecessary blank space.

h=BreakPlot(x,y,y_break_start,y_break_end,break_type)
function h=BreakPlot(x,y,y_break_start,y_break_end,break_type)
% BreakPlot(x,y,y_break_start,y_break_end,break_type)
% Produces a plot who's y-axis skips to avoid unecessary blank space
% 
% INPUT
% x
% y
% y_break_start
% y_break_end
% break_type
%    if break_type='RPatch' the plot will look torn
%       in the broken space
%    if break_type='Patch' the plot will have a more
%       regular, zig-zag tear
%    if break_plot='Line' the plot will merely have
%       some hash marks on the y-axis to denote the
%       break
%
% USAGE:
% figure;
% BreakPlot(rand(1,21),[1:10,40:50],10,40,'Line');
% figure;
% BreakPlot(rand(1,21),[1:10,40:50],10,40,'Patch');
% figure;
% BreakPlot(rand(1,21),[1:10,40:50],10,40,'RPatch');
% figure;
% x=rand(1,21);y=[1:10,40:50];
% subplot(2,1,1);plot(x(y>=40),y(y>=40),'.');
% set(gca,'XTickLabel',[]);
% subplot(2,1,2);plot(x(y<=20),y(y<=20),'.');
%
% IT'S NOT FANCY, BUT IT WORKS.

% Michael Robbins
% robbins@bloomberg.net
% michael.robbins@bloomberg.net

% data
if nargin<5 break_type='RPatch'; end;
if nargin<4 y_break_end=40; end;
if nargin<3 y_break_start=10; end;
if nargin<2 y=[1:10,40:50]; end;
if nargin<1 x=rand(1,21); end;


y_break_mid=(y_break_end-y_break_start)./2+y_break_start;

% erase useless data
x(y>y_break_start & y <y_break_end)=[];
y(y>y_break_start & y <y_break_end)=[];

% leave room for the y_break_end
[junk,i]=min(y>=y_break_end);
if i>y_break_end
    x=[x(1:i-1) NaN x(i:end)];
    y=[y(1:i-1) y_break_mid y(i:end)];
end;

% remap
y2=y;
y2(y2>=y_break_end)=y2(y2>=y_break_end)-y_break_mid;

% plot
h=plot(x,y2,'.');

% make break
xlim=get(gca,'xlim');
ytick=get(gca,'YTick');
[junk,i]=min(ytick<=y_break_start);
y=(ytick(i)-ytick(i-1))./2+ytick(i-1);
dy=(ytick(2)-ytick(1))./10;
xtick=get(gca,'XTick');
x=xtick(1);
dx=(xtick(2)-xtick(1))./2;

switch break_type
    case 'Patch',
		% this can be vectorized
        dx=(xlim(2)-xlim(1))./10;
        yy=repmat([y-2.*dy y-dy],1,6);
        xx=xlim(1)+dx.*[0:11];
		patch([xx(:);flipud(xx(:))], ...
            [yy(:);flipud(yy(:)-2.*dy)], ...
            [.8 .8 .8])
    case 'RPatch',
		% this can be vectorized
        dx=(xlim(2)-xlim(1))./100;
        yy=y+rand(101,1).*2.*dy;
        xx=xlim(1)+dx.*(0:100);
		patch([xx(:);flipud(xx(:))], ...
            [yy(:);flipud(yy(:)-2.*dy)], ...
            [.8 .8 .8])
    case 'Line',
		line([x-dx x   ],[y-2.*dy y-dy   ]);
		line([x    x+dx],[y+dy    y+2.*dy]);
		line([x-dx x   ],[y-3.*dy y-2.*dy]);
		line([x    x+dx],[y+2.*dy y+3.*dy]);
end;
set(gca,'xlim',xlim);

% map back
ytick(ytick>y_break_start)=ytick(ytick>y_break_start)+y_break_mid;
for i=1:length(ytick)
   yticklabel{i}=sprintf('%d',ytick(i));
end;
set(gca,'yticklabel',yticklabel);

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