matlab箭头函数，包括两个箭头函数以及一个例子

function H = arrowPlot(X,Y,varargin) %ARROWPLOT Plot with arrow on the curve. % ARROWPLOT(X, Y) plots X, Y vectors with 2 arrows directing the trend of data. % % You can use some options to edit the properties of arrow or curve. % The options that you can change are as follow: % number: The number of arrows, default number is 2; % color: The color of arrows and curve, default color is [0, 0.447, 0.741]; % LineWidth: The line width of curve, default LineWidth is 0.5; % scale: To scale the size of arrows, default scale is 1; % limit: The range to plot, default limit is determined by X, Y data; % ratio: The ratio of X-axis and Y-axis, default ratio is determined by X, Y data; % You can use 'equal' for 'ratio', that means 'ratio' value is [1, 1, 1]. % % Example 1: % --------- % t = [0:0.01:20]; % x = t.*cos(t); % y = t.*sin(t); % arrowPlot(x, y, 'number', 3) % % Example 2: % --------- % t = [0:0.01:20]; % x = t.*cos(t); % y = t.*sin(t); % arrowPlot(x, y, 'number', 5, 'color', 'r', 'LineWidth', 1, 'scale', 0.8, 'ratio', 'equal') % Copyright 2017 TimeCoder. h = plot(X,Y); hold on; if nargout == 1 H = h; end ratio = get(gca, 'DataAspectRatio'); limit = axis; d = max(limit(2)-limit(1), limit(4)-limit(3)); default_options.number = 2; default_options.color = [0 0.447 0.741]; default_options.LineWidth = 0.5; default_options.size = d; default_options.scale = 1; default_options.limit = axis; default_options.ratio = ratio; Options = creat_options(varargin, default_options); useroptions = creat_useroptions(varargin); if ~isfield(useroptions, 'size') Options.size = max(Options.limit(2)-Options.limit(1), Options.limit(4)-Options.limit(3)); end if ~isfield(useroptions, 'ratio') axis(Options.limit); Options.ratio = get(gca, 'DataAspectRatio'); end set(h, 'color', Options.color); set(h, 'LineWidth', Options.LineWidth); if isa(Options.ratio, 'char') && strcmp(Options.ratio, 'equal') r = 1; else r = Options.ratio(2) / Options.ratio(1); end n_X = length(X); journey = 0; for i = 1 : n_X-1 journey = journey + sqrt( (X(i+1)-X(i))^2 + (Y(i+1)-Y(i))^2 ); end journey_part = journey / Options.number; if 10*journey<Options.size Options.size = 10*journey; end [X_arrow, Y_arrow] = arrow_shape(50, 25); [X_arrow1, Y_arrow1] = Scale(X_arrow, Y_arrow, 0.015*Options.scale*Options.size); k=0.5;%%%很重要，改变箭头位置 journey_now =0; for i = 2: n_X-2 journey_step = sqrt( (X(i+1)-X(i))^2 + (Y(i+1)-Y(i))^2 ); journey_next = journey_now + journey_step; if journey_now<=k*journey_part && journey_next>k*journey_part s = (k*journey_part - journey_now) / journey_step; x0 = X(i) + s * (X(i+1)-X(i)); y0 = Y(i) + s * (Y(i+1)-Y(i)); [X_arrow2, Y_arrow2] = Rotate(X_arrow1, Y_arrow1, arg(X(i+1)-X(i), (Y(i+1)-Y(i))/r)); [X_arrow3, Y_arrow3] = Translation(X_arrow2, r*Y_arrow2, [x0, y0]); g = fill(X_arrow3, Y_arrow3, Options.color); set(g, 'EdgeColor', Options.color); k=k+1; end journey_now = journey_next;%%%这里很重要 end axis(Options.limit); if isequal(Options.ratio, 'equal') axis equal; end hold off; end function Options = creat_options(user_choice, default_choice_struct) n = length(user_choice); if ~ispair(n) error('varargin is not an options''s struct.'); end Options = default_choice_struct; i = 1; while i <= n if isfield(default_choice_struct, user_choice{i}) Options = setfield(Options, user_choice{i}, user_choice{i+1}); end i = i + 2; end end function Options = creat_useroptions(VARARGIN) if ~isa(VARARGIN, 'cell') error('VARARGIN is not of class cell!'); end n = length(VARARGIN); if ~ispair(n) error('length of VARARGIN is not pair!'); end i = 1; Options = struct(); while i < n Options = setfield(Options, VARARGIN{i}, VARARGIN{i+1}); i = i+2; end end function check = ispair(x) check = ( isint(x) && isint( 1.0*x / 2.0 ) ); end function check = isint(x) check = ( floor(x) == x ); end function theta = arg(x,y) if nargin== 2 [m, n] = size(x); theta = zeros(m, n); for i = 1 : m for j = 1 : n if x(i, j) > 0 || y(i, j) ~= 0 theta(i, j) =2 *atan( y(i, j) ./ ( x(i, j)-sqrt(x(i, j).^2+y(i,j).^2) ) );%%%%%改变方向,这里的+号很关键 elseif x(i, j) < 0 && y(i, j) == 0 theta(i, j) = -pi;%%%%%%% elseif x(i, j) == 0 && y(i, j) == 0 theta(i, j) = 0; end end end elseif nargin==1 theta = arg(real(x), imag(x)); end end function [X, Y] = arrow_shape(theta1, theta2) theta1 = theta1/180*pi; theta2 = theta2/180*pi; x0 = tan(theta2) / ( tan(theta2) - tan(theta1) ); y0 = tan(theta1) * tan(theta2) / ( tan(theta2) - tan(theta1) ); X = [0, x0, 1, x0, 0]; Y = [0, y0, 0, -y0, 0]; end function [X_new, Y_new] = Rotate( X, Y, varargin ) if length(varargin)==1 center = [0, 0]; theta = varargin{1}; elseif length(varargin)==2 center = varargin{1}; theta = varargin{2}; end [m1, n1] = size(X); [m2, n2] = size(Y); if min(m1, n1) ~= 1 error('The size of X is wrong!'); end if min(m2, n2) ~= 1 error('The size of Y is wrong!'); end if n1 == 1 X = X'; end if n2 == 1 Y = Y'; end if length(X) ~= length(Y) error('length(X) and length(Y) must be equal!'); end XY_new = [cos(theta), -sin(theta); sin(theta), cos(theta)] * [X-center(1); Y-center(2)]; X_new = XY_new(1, :)+center(1); Y_new = XY_new(2, :)+center(2); end function [X_new, Y_new] = Scale( X, Y, varargin ) if length(varargin)==1 center = [0, 0]; s = varargin{1}; elseif length(varargin)==2 center = varargin{1}; s = varargin{2}; end X_new = s * ( X - center(1) ) + center(1); Y_new = s * ( Y - center(2) ) + center(2); end function [X_new, Y_new] = Translation( X, Y, increasement ) X_new = X + increasement(1); Y_new = Y + increasement(2); end