今天我们要学习，如何在figure中添加注释， 并指向方向。

首先画出数据，并添加一条均值线

Line([mean1 mean1], get(gca,’ylim’));

如图：

添加文本连接指向均值线，使用dsxy2figxy从数据空间转换点或位置坐标进入标准的图坐标中，annotation添加图像的注释文本，即指向均值线

function varargout = dsxy2figxy(varargin)

if length(varargin{1}) == 1 && ishandle(varargin{1}) ...

&& strcmp(get(varargin{1},'type'),'axes')

hAx = varargin{1};

varargin = varargin(2:end); % Remove arg 1 (axes handle)

else

hAx = gca;

end;

% Remaining args are either two point locations or a position vector

if length(varargin) == 1 % Assume a 4-element position vector

pos = varargin{1};

else

[x,y] = deal(varargin{:}); % Assume two pairs (start, end points)

end

% Get limits

axun = get(hAx,'Units');

set(hAx,'Units','normalized'); % Make axes units normalized

axpos = get(hAx,'Position'); % Get axes position

axlim = axis(hAx); % Get the axis limits [xlim ylim (zlim)]

axwidth = diff(axlim(1:2));

axheight = diff(axlim(3:4));

% Transform from data space coordinates to normalized figure coordinates

if exist('x','var') % Transform a and return pair of points

varargout{1} = (x - axlim(1)) * axpos(3) / axwidth + axpos(1);

varargout{2} = (y - axlim(3)) * axpos(4) / axheight + axpos(2);

else % Transform and return a position rectangle

pos(1) = (pos(1) - axlim(1)) / axwidth * axpos(3) + axpos(1);

pos(2) = (pos(2) - axlim(3)) / axheight * axpos(4) + axpos(2);

pos(3) = pos(3) * axpos(3) / axwidth;

pos(4) = pos(4) * axpos(4 )/ axheight;

varargout{1} = pos;

end

% Restore axes units

set(hAx,'Units',axun)

完整代码：

plot(x,y1);

%% Add the |line| at the mean position

line([mean1 mean1],get(gca,'ylim'));

%% Add the |text arrow| annotation, working from data space annotation

% Convert to norm fig units

[xmeannfu ymeannfu]= dsxy2figxy(gca,[.5,0],[.15,.05]);

% Add the annotation component

annotation('textarrow',xmeannfu,ymeannfu,'String','Mean');

title({'The standard normal probability distribution',...

' function is plotted with the mean pointed out with', ...

'a text arrow to make the figure more informative'});

xlabel('x');ylabel('probability of x');

set(gcf,'Paperpositionmode','auto','Color',[1 1 1]);

结果图：