最近画的一幅图的X轴是时间，需要标注月份、日期和时分，显然每个xticklabel太长了，于是想要分两行标注，第一行标注时分，第二行标注月日。搜了一圈发现MATLAB并没有实现这个功能的函数，于是只能使用text行数进行实现。实现过程主要是先调整gca的宽度，然后上移为两行text腾出空间。然后设置gca本身的xticklabels为空。根据xticks的位置和y轴的范围设置两行text的范围，最后下移xlabel的范围。
画完之后又发现colorbar太宽了，看起来不美观。结果调整colorbar position之后，gca竟然自动调整了宽度，导致gca和colorbar重叠了，于是又设置了一遍gca的position。下面是示例代码，总体顺序是
(1)画图
(2)画colorbar
(3)调整gca position
(4)标注两行text
(5)调整xlabel的position
(6)调整colorbar的position
(7)重置gca position
clc;clear;
figure;
pcolor(0:10,1:20,rand(20,11));shading interp;
c=colorbar;colormap(cool);
%plot colorbar first and get gca position
ax=gca;
xticks(0:2:10);
xlim([0 10]);
%% add two lines of xitck labels
xticklabels('');
% narrow gca and move up to make space for two lines of xitck labels
ax.Position=[ax.Position(1),ax.Position(2)+ax.Position(4)*0.3,ax.Position(3),ax.Position(4)*0.7];
xTicks = get(gca, 'xtick');
XtickLabelStrs{
1}={
' 00:00';' 12:00';' 00:00';' 12:00';' 00:00';' 12:00'};
XtickLabelStrs{
2}={
'Jan 24';'Jan 24';'Jan 25';'Jan 25';'Jan 26';'Jan 26'};
xl=xlim; minX=xl(1);maxX=xl(2);
yl=ylim; minY=yl(1);maxY=yl(2);
% You will have to adjust the offset based on the size of figure
VerticalOffset = (maxY-minY)*0.2;
for xx = 1:length(xTicks)
% Create a text box at every Tick label position
text(xTicks(xx), minY-VerticalOffset, ...
[XtickLabelStrs{
1}(xx);XtickLabelStrs{
2}(xx)],...
'fontsize',9,...
'HorizontalAlignment','center');
% 'HorizontalAlignment','center' specifies that the elements of the different lines
% will be center aligned
end
xlabel('Time [UT]','position',[(minX+maxX)/2,minY-VerticalOffset*2]);
ylabel('Frequency [mHz]');
%% set colorbar width
GcaPosition=ax.Position;
c.Position=[c.Position(1),c.Position(2),c.Position(3)*0.6,c.Position(4)];
% because the gca position will change automaticlly, so you need to reset
% the position of gca as previous;
ax.Position=GcaPosition;
