題目：在Matlab中使用barweb繪製帶方差的分組柱狀圖時的幾個注意事項
注：本人電腦上安裝有Matlab r2009b, r2014a, r2017b三個Matlab版本，其中r2009b, r2014a對應文中提到的Matlab低版本，r2017b對應文中提到的Matlab高版本；程序在本人電腦上的測試通過，不同Matlab可能會出現新的問題。
Matlab自帶的bar加上errorbar功能有限，不能繪製有分組情況下的帶方差的柱狀圖（bar本身可以繪製有分組的柱狀圖但不能帶方差，bar+errorbar聯合使用可繪製帶方差的柱狀圖但不能分組），此時一般使用barweb函數，這是一個由第三方個人編寫的函數，鏈接如下：
https://ww2.mathworks.cn/matlabcentral/fileexchange/10803-barweb-bargraph-with-error-bars
編寫如下示例程序barweb_demo.m：
（注：由於數據X和E均由rand隨機生成的，所以每次運行所得圖形是不同的）：
%barweb使用舉例@2019-09-04
close all;clear;clc;
X = 5+rand(6,3);%隨機生成數據
E = rand(6,3);%隨機生成誤差
legends = {'Type-I','Type-II','Type-III'};
groupnames = cell(6,1);
groupnames{1} = 'Group1';groupnames{2} = 'Group2';groupnames{3} = 'Group3';
groupnames{4} = 'Group4';groupnames{5} = 'Group5';groupnames{6} = 'Group6';
Title = 'title of barweb example';
Xlabel = 'xlabel of barweb example';
Ylabel = 'ylabel of barweb exampe';
barweb(X,E,1,groupnames,Title,Xlabel,Ylabel,jet,'none',legends,2,'plot');
若你的Matlab版本比較低，例如Matlab R2014，那麼應該可以正常運行：
注：如果不想顯示橫軸、縱軸、圖片標題，則將對應的參數用[]替代即可，例如：
barweb(X,E,1,groupnames,Title,[],Ylabel,jet,'none',legends,2,'plot');
則將不再顯示橫軸的“xlabel of barweb example”內容；
但你的若Matlab版本比較高，例如Matlab R2017，運行時會出錯：
這時可能會看到barweb主頁上的評論：
即出錯位置在原程序的如下位置：
將以上兩行註釋掉，換成：
x = handles.bars(i).XData + handles.bars(i).XOffset;
這時再運行示例程序barweb_demo.m就不報錯了：
你會發現那個legend顯示是有問題的，除了想要的Type-I、Type-II、Type-III之外，還有多餘的data1、data2、data3（另外legend顯示的位置也有問題，這個後面再說）。這個是因爲原先138~143行繪製legend的代碼有問題：
只要將這段代碼換個位置，剪切至%Plot erros部分的for循環之後就可以了，如下：
這時再次運行示例程序barweb_demo.m，一切就正常了：
但是，倘若有一天你又在低版本Matlab上使用該修改過後的程序，發現又會報錯：
其實，原作者的程序是沒錯的。之所以部分人直接運行時會報錯，主要是由於不同版本的Matlab軟件中函數bar的返回值不同。在Matlab的Command Window中輸入命令help bar，然後打開函數bar的幫助文檔：
以下是Matlab r2009b中的幫助文檔部分截圖：
以下是Matlab r2014a中的幫助文檔部分截圖：
以下是Matlab r2017b中的幫助文檔部分截圖：
對比一下可以發現，R2009b和R2014a的返回值是a vector of handles，而R2017b的返回值是one or more Bar objects，原作者的程序只適用於返回值是a vector of handles的Matlab版本，而按barweb主頁上的評論修改後的程序只適用於返回值是one or more Bar objects的Matlab版本。所以具體使用哪個版本，要自己根據自己的Matlab版本中bar函數的返回值確定。爲了使修改後的barweb函數適應不同Matlab版本中bar函數這兩種不同的返回值，可將%Plot erros部分的for循環做如下修改：
也就是使用if…else…語句判斷bar函數返回值的類型，進而選擇執行相應的代碼。
對於legend顯示的位置問題，只要針對性修改如下代碼即可：
可以發現，目前legend顯示位置’location’的參數值爲’best’，可以把這個參數值去掉，即將原代碼第139行改爲
handles.legend = legend(bw_legend, 'fontsize', 12);
此時legend會按’location’ 的默認參數設置，顯示在圖形的左上角：
另外還可以將接下來的legend boxoff;註釋掉，legend示例會有邊框：
當然還可以修改上面的’fontsize’參數，改變legend示例的字號大小；更多設置那就自己摸索吧。
另外，還可能要修改圖形的標題、橫軸、縱軸的顯示格式，尤其是字號大小，可通過barweb函數的如下代碼修改：
if ~isempty(bw_title)
title(bw_title, 'fontsize',14);
end
if ~isempty(bw_xlabel)
xlabel(bw_xlabel, 'fontsize',14);
end
if ~isempty(bw_ylabel)
ylabel(bw_ylabel, 'fontsize',14);
end
相信一般人都熟悉使用title, xlabel, ylabel三個函數分別設置figure的標題、橫軸、縱軸。
若想修改group的內容，即本例中橫軸的Group1~Group6的格式，應該修改barweb原來的第180行：
set(gca, 'xticklabel', groupnames, 'box', 'off', 'ticklength', [0 0], 'fontsize', 12, 'xtick',1:numgroups, 'linewidth', 2,'xgrid','off','ygrid','off');
更多修改設置可以大致瀏覽一下barweb函數源碼；實際上，barweb就是結合了bar和errorbar兩個函數，關鍵是errorbar不能適用於帶分組的情形，因此特別調整了一下而已。
最後，說一個圖片存儲的技巧：平時可以使用“文件--->另存爲”（save as），選擇自己想要的格式保存即可，但如此存儲的圖片白色邊框會比較大。還可以運行如下語句保存圖片：
print('barweb_example','-depsc2','-r600');
其中，barweb_example是文件名，-depsc2是文件格式，-r600是圖片分辨率。可以help print，打開print函數的幫助文檔查看，例如對-depsc2參數的解釋：
即存儲爲EPS彩色圖片；
對-r600的解釋：
即此處的number=600。單獨運行以上語句時，若有多張圖片，最新單擊瀏覽了哪張圖片就會存儲哪張圖片。
這裏的柱狀圖的填充顏色都是隨機的，如果黑白打印的話顯示效果就不好了，如果能用不同的條紋填充就最好了，這時可以使用另外一個第三方個人寫的函數：applyhatch，鏈接如下：
http://www.aos.wisc.edu/~dvimont/matlab/Graphics_Tools/applyhatch.html
或者applyhatch_plusC，鏈接如下：
https://ww2.mathworks.cn/matlabcentral/fileexchange/26797-applyhatch_plusc
但效果並不是特別好，這裏就不說了，需要的話可以自行探索使用方法。
附錄1：barweb修改後的代碼（兼容多版本Matlab，修改了原先138~143行繪製legend的代碼）
function handles = barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, error_sides, legend_type)
%
% Usage: handles = barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, error_sides, legend_type)
%
% Ex: handles = barweb(my_barvalues, my_errors, [], [], [], [], [], bone, [], bw_legend, 1, 'axis')
%
% barweb is the m-by-n matrix of barvalues to be plotted.
% barweb calls the MATLAB bar function and plots m groups of n bars using the width and bw_colormap parameters.
% If you want all the bars to be the same color, then set bw_colormap equal to the RBG matrix value ie. (bw_colormap = [1 0 0] for all red bars)
% barweb then calls the MATLAB errorbar function to draw barvalues with error bars of length error.
% groupnames is an m-length cellstr vector of groupnames (i.e. groupnames = {'group 1'; 'group 2'}). For no groupnames, enter [] or {}
% The errors matrix is of the same form of the barvalues matrix, namely m group of n errors.
% Gridstatus is either 'x','xy', 'y', or 'none' for no grid.
% No legend will be shown if the legend paramter is not provided
% 'error_sides = 2' plots +/- std while 'error_sides = 1' plots just + std
% legend_type = 'axis' produces the legend along the x-axis while legend_type = 'plot' produces the standard legend. See figure for more details
%
% The following default values are used if parameters are left out or skipped by using [].
% width = 1 (0 < width < 1; widths greater than 1 will produce overlapping bars)
% groupnames = '1', '2', ... number_of_groups
% bw_title, bw_xlabel, bw_ylabel = []
% bw_color_map = jet
% gridstatus = 'none'
% bw_legend = []
% error_sides = 2;
% legend_type = 'plot';
%
% A list of handles are returned so that the user can change the properties of the plot
% handles.ax: handle to current axis
% handles.bars: handle to bar plot
% handles.errors: a vector of handles to the error plots, with each handle corresponding to a column in the error matrix
% handles.legend: handle to legend
%
%
% See the MATLAB functions bar and errorbar for more information
%
% Author: Bolu Ajiboye
% Created: October 18, 2005 (ver 1.0)
% Updated: Dec 07, 2006 (ver 2.1)
% Updated: July 21, 2008 (ver 2.3)
% Get function arguments
if nargin < 2
error('Must have at least the first two arguments: barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, barwebtype)');
elseif nargin == 2
width = 1;
groupnames = 1:size(barvalues,1);
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 3
groupnames = 1:size(barvalues,1);
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 4
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 5
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 6
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 7
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 8
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 9
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 10
error_sides = 2;
legend_type = 'plot';
elseif nargin == 11
legend_type = 'plot';
end
change_axis = 0;
ymax = 0;
if size(barvalues,1) ~= size(errors,1) || size(barvalues,2) ~= size(errors,2)
error('barvalues and errors matrix must be of same dimension');
else
if size(barvalues,2) == 1
barvalues = barvalues';
errors = errors';
end
if size(barvalues,1) == 1
barvalues = [barvalues; zeros(1,length(barvalues))];
errors = [errors; zeros(1,size(barvalues,2))];
change_axis = 1;
end
numgroups = size(barvalues, 1); % number of groups
numbars = size(barvalues, 2); % number of bars in a group
if isempty(width)
width = 1;
end
% Plot bars
handles.bars = bar(barvalues, width, 'edgecolor','k', 'linewidth', 2);
hold on
if ~isempty(bw_colormap)
colormap(bw_colormap);
else
colormap(jet);
end
% Plot erros
for i = 1:numbars
bar_versions = class(handles.bars(i));
if strcmp(bar_versions,'double')
x =get(get(handles.bars(i),'children'), 'xdata');
x = mean(x([1 3],:));
else
x = handles.bars(i).XData + handles.bars(i).XOffset;
end
handles.errors(i) = errorbar(x, barvalues(:,i), errors(:,i), 'k', 'linestyle', 'none', 'linewidth', 2);
ymax = max([ymax; barvalues(:,i)+errors(:,i)]);
end
if ~isempty(bw_legend) && ~strcmp(legend_type, 'axis')
handles.legend = legend(bw_legend, 'fontsize',12);%'location', 'best',
% legend boxoff;
else
handles.legend = [];
end
if error_sides == 1
set(gca,'children', flipud(get(gca,'children')));
end
ylim([0 ymax*1.1]);
xlim([0.5 numgroups-change_axis+0.5]);
if strcmp(legend_type, 'axis')
for i = 1:numbars
xdata = get(handles.errors(i),'xdata');
for j = 1:length(xdata)
text(xdata(j), -0.03*ymax*1.1, bw_legend(i), 'Rotation', 60, 'fontsize', 12, 'HorizontalAlignment', 'right');
end
end
set(gca,'xaxislocation','top');
end
if ~isempty(bw_title)
title(bw_title, 'fontsize',14);
end
if ~isempty(bw_xlabel)
xlabel(bw_xlabel, 'fontsize',14);
end
if ~isempty(bw_ylabel)
ylabel(bw_ylabel, 'fontsize',14);
end
set(gca, 'xticklabel', groupnames, 'box', 'off', 'ticklength', [0 0], 'fontsize', 12, 'xtick',1:numgroups, 'linewidth', 2,'xgrid','off','ygrid','off');
if ~isempty(gridstatus) && any(gridstatus == 'x')
set(gca,'xgrid','on');
end
if ~isempty(gridstatus) && any(gridstatus == 'y')
set(gca,'ygrid','on');
end
handles.ax = gca;
hold off
end
附錄2：barweb原來代碼（可以在開篇給出的鏈接中複製，放在此處僅作備份）
function handles = barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, error_sides, legend_type)
%
% Usage: handles = barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, error_sides, legend_type)
%
% Ex: handles = barweb(my_barvalues, my_errors, [], [], [], [], [], bone, [], bw_legend, 1, 'axis')
%
% barweb is the m-by-n matrix of barvalues to be plotted.
% barweb calls the MATLAB bar function and plots m groups of n bars using the width and bw_colormap parameters.
% If you want all the bars to be the same color, then set bw_colormap equal to the RBG matrix value ie. (bw_colormap = [1 0 0] for all red bars)
% barweb then calls the MATLAB errorbar function to draw barvalues with error bars of length error.
% groupnames is an m-length cellstr vector of groupnames (i.e. groupnames = {'group 1'; 'group 2'}). For no groupnames, enter [] or {}
% The errors matrix is of the same form of the barvalues matrix, namely m group of n errors.
% Gridstatus is either 'x','xy', 'y', or 'none' for no grid.
% No legend will be shown if the legend paramter is not provided
% 'error_sides = 2' plots +/- std while 'error_sides = 1' plots just + std
% legend_type = 'axis' produces the legend along the x-axis while legend_type = 'plot' produces the standard legend. See figure for more details
%
% The following default values are used if parameters are left out or skipped by using [].
% width = 1 (0 < width < 1; widths greater than 1 will produce overlapping bars)
% groupnames = '1', '2', ... number_of_groups
% bw_title, bw_xlabel, bw_ylabel = []
% bw_color_map = jet
% gridstatus = 'none'
% bw_legend = []
% error_sides = 2;
% legend_type = 'plot';
%
% A list of handles are returned so that the user can change the properties of the plot
% handles.ax: handle to current axis
% handles.bars: handle to bar plot
% handles.errors: a vector of handles to the error plots, with each handle corresponding to a column in the error matrix
% handles.legend: handle to legend
%
%
% See the MATLAB functions bar and errorbar for more information
%
% Author: Bolu Ajiboye
% Created: October 18, 2005 (ver 1.0)
% Updated: Dec 07, 2006 (ver 2.1)
% Updated: July 21, 2008 (ver 2.3)
% Get function arguments
if nargin < 2
error('Must have at least the first two arguments: barweb(barvalues, errors, width, groupnames, bw_title, bw_xlabel, bw_ylabel, bw_colormap, gridstatus, bw_legend, barwebtype)');
elseif nargin == 2
width = 1;
groupnames = 1:size(barvalues,1);
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 3
groupnames = 1:size(barvalues,1);
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 4
bw_title = [];
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 5
bw_xlabel = [];
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 6
bw_ylabel = [];
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 7
bw_colormap = jet;
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 8
gridstatus = 'none';
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 9
bw_legend = [];
error_sides = 2;
legend_type = 'plot';
elseif nargin == 10
error_sides = 2;
legend_type = 'plot';
elseif nargin == 11
legend_type = 'plot';
end
change_axis = 0;
ymax = 0;
if size(barvalues,1) ~= size(errors,1) || size(barvalues,2) ~= size(errors,2)
error('barvalues and errors matrix must be of same dimension');
else
if size(barvalues,2) == 1
barvalues = barvalues';
errors = errors';
end
if size(barvalues,1) == 1
barvalues = [barvalues; zeros(1,length(barvalues))];
errors = [errors; zeros(1,size(barvalues,2))];
change_axis = 1;
end
numgroups = size(barvalues, 1); % number of groups
numbars = size(barvalues, 2); % number of bars in a group
if isempty(width)
width = 1;
end
% Plot bars
handles.bars = bar(barvalues, width,'edgecolor','k', 'linewidth', 2);
hold on
if ~isempty(bw_colormap)
colormap(bw_colormap);
else
colormap(jet);
end
if ~isempty(bw_legend) && ~strcmp(legend_type, 'axis')
handles.legend = legend(bw_legend, 'location', 'best', 'fontsize',12);
legend boxoff;
else
handles.legend = [];
end
% Plot erros
for i = 1:numbars
x =get(get(handles.bars(i),'children'), 'xdata');
x = mean(x([1 3],:));
handles.errors(i) = errorbar(x, barvalues(:,i), errors(:,i), 'k', 'linestyle', 'none', 'linewidth', 2);
ymax = max([ymax; barvalues(:,i)+errors(:,i)]);
end
if error_sides == 1
set(gca,'children', flipud(get(gca,'children')));
end
ylim([0 ymax*1.1]);
xlim([0.5 numgroups-change_axis+0.5]);
if strcmp(legend_type, 'axis')
for i = 1:numbars
xdata = get(handles.errors(i),'xdata');
for j = 1:length(xdata)
text(xdata(j), -0.03*ymax*1.1, bw_legend(i), 'Rotation', 60, 'fontsize', 12, 'HorizontalAlignment', 'right');
end
end
set(gca,'xaxislocation','top');
end
if ~isempty(bw_title)
title(bw_title, 'fontsize',14);
end
if ~isempty(bw_xlabel)
xlabel(bw_xlabel, 'fontsize',14);
end
if ~isempty(bw_ylabel)
ylabel(bw_ylabel, 'fontsize',14);
end
set(gca, 'xticklabel', groupnames, 'box', 'off', 'ticklength', [0 0], 'fontsize', 12, 'xtick',1:numgroups, 'linewidth', 2,'xgrid','off','ygrid','off');
if ~isempty(gridstatus) && any(gridstatus == 'x')
set(gca,'xgrid','on');
end
if ~isempty(gridstatus) && any(gridstatus == 'y')
set(gca,'ygrid','on');
end
handles.ax = gca;
hold off
end