如何对齐MATLAB子图？

Question

My MATLAB subplots are not aligned perfectly, see the green rectangle in figure below . How to avoid this shift?

Here is what I am trying

clear all;
clc;

RF=RF_data(:,2:end);

figure

subplot(3,4,1)

pos_pre = 1.3:1:3.3;    % for positioning

boxplot(RF(2:71,[45,47,46]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '}) 
hold on  

pos_post = 1.55:1:3.55;   % Ignore this comment

boxplot(RF(72:end,[45,47,46]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:3.5)  
set(gca,'XTickLabel',{'10a', '10b', '10c'}, 'FontSize', 7)

X = get(gca,'XLim');  
Y = get(gca,'YLim');
hold off 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

subplot(3,4,2)

pos_pre = 1.3:1:3.3;   % Ignore this comment

boxplot(RF(2:71,[17,16,15]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:3.55;  % Ignore this comment

boxplot(RF(72:end,[17,16,15]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:3.5) 
set(gca,'XTickLabel',{'7a', '7b', '7c'}, 'FontSize', 7) 

hold off 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

subplot(3,4,3)

pos_pre = 1.3:1:3.3;  % Ignore this comment

boxplot(RF(2:71,[54, 53, 52]),'colors','b',...
    'positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:3.55;  

boxplot(RF(72:end,[54, 53, 52]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:3.5)  
set(gca,'XTickLabel',{'6a', '6b', '6c', '6d', '6e', '6f', '6g'}, 'FontSize', 7)

hold off 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

subplot(3,4,4)

pos_pre = 1.3:1:3.3;  

boxplot(RF(2:71,[76,75,74]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:3.55;  

boxplot(RF(72:end,[76,75,74]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:3.5)  
set(gca,'XTickLabel',{'5a', '5b', '5c', '5d', '5e', '5f', '5g', '5h'}, 'FontSize', 7)

X = get(gca,'XLim');  
Y = get(gca,'YLim');
hold off 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
subplot(3,4,(5:6))

pos_pre = 1.3:1:8.3;  

boxplot(RF(2:71,[32,31,30,50,62,85,86,34]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:8.55;  

boxplot(RF(72:end,[32,31,30,50,62,85,86,34]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:8.5)
set(gca,'XTickLabel',{'5a', '5b', '5c', '5d', '5e', '5f', '5g', '5h'}, 'FontSize', 7)

hold off 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

subplot(3,4,(7:8))

pos_pre = 1.3:1:7.3;  

boxplot(RF(2:71,[12, 11, 42, 41, 40, 79, 78]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:7.55;  

boxplot(RF(72:end,[12, 11, 42, 41, 40, 79, 78]),'colors','r',...
    'positions',pos_post,'width',0.18,'symbol', 'rd','OutlierSize',3,...
    'factorseparator',1); 

set(gca,'XTick',1.5:1:7.5) 
set(gca,'XTickLabel',{'6a', '6b', '6c', '6d', '6e', '6f', '6g'}, 'FontSize', 7)

hold off 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
subplot(3,4,(9:12))

pos_pre = 1.3:1:19.3;  

boxplot(RF(2:71,[1,63,89,88,87,27,80,33,26,28,39,9,21,72,77,19,18,38,5]),...
    'colors','b','positions',pos_pre,'width',0.18,...
    'symbol', 'bd', 'OutlierSize',3);
set(gca,'XTickLabel',{' '})  
hold on  

pos_post = 1.55:1:19.55;  

boxplot(RF(72:end,[1,63,89,88,87,27,80,33,26,28,39,9,21,72,7,19,18,38,5]),...
    'colors','r','positions',pos_post,'width',0.18,'symbol', 'rd',...
    'OutlierSize',3,'factorseparator',1); 

set(gca,'XTick',1.5:1:19.5)
set(gca,'XTickLabel',{'2a', '2b', '2c', '2d', '2e', '2f', '2g','2e','2f','2g','2h',...
    '2i','2j','2k','2l','2m','2n','2o','2p','2q','2r','2s'}, 'FontSize', 7)


X = get(gca,'XLim');  
Y = get(gca,'YLim');
hold off 

text('Position',[0.85*X(1,2), 0.9*Y(1,2)],'String','1901-1970',...
    'color', 'b', 'FontWeight', 'bold', 'FontSize', 8) 

text('Position',[0.85*X(1,2), 0.8*Y(1,2)],'String','1971-2013',...
    'color', 'r', 'FontWeight', 'bold', 'FontSize', 8) 

%%
disp('Done')

It's asking to add some more detail, so I am just writing random stuff.

Answer 1

I don't see a problem in this example:

% first row
subplot(3,4,1), plot(cumsum(randn(100,1)))
subplot(3,4,2), plot(cumsum(randn(100,1)))
subplot(3,4,3), plot(cumsum(randn(100,1)))
subplot(3,4,4), plot(cumsum(randn(100,1)))

% second row
subplot(3,2,3), plot(cumsum(randn(100,1)))
subplot(3,2,4), plot(cumsum(randn(100,1)))

% third row
subplot(3,1,3), plot(cumsum(randn(100,1)))

---

EDIT:

Using the code you posed, a quick solution is to manually adjust the axes positions to be aligned.

First you need to store the handles of all subplot. So add the followings to your script:

figure
h = zeros(1,7);

h(1) = subplot(3,4,1);
% ... [snip] ...

h(2) = subplot(3,4,2);
% ... [snip] ...

% ...

h(7) = subplot(3,4,(9:12));
% ... [snip] ...

Then you can do something like this:

% positions of axes on the left
positions = cell2mat(get(h([1 5 7]), 'Position'));

% minimum x-position
x = min(positions(:,1));

% set them to be left aligned, and just the width accordingly
for i=[1 5 7]
    pos = get(h(i), 'Position');
    set(h(i), 'Position',[x, pos(2), pos(3) + (pos(1) - x), pos(4)]);
end

Here is the result I get (I used random data RF_data = rand(100,100); to run the script):