根据条件为图形背景的特定区域着色

Question

我有一个条形图 (2D)，我想将另一个向量的值 > 1 的部分的背景设为红色，即

示例：

图 = [2 3 5 4 9 1 7] 颜色 = [0 2 2 1 0 1 2]

因此条形图将显示通常的条形图，并且后面的背景（包括条形之间的空间）在“3”、“5”和“7”（位置 2、3、7）的条形后面被涂成红色

蓝色示例：

这有可能吗？

谢谢

Answer 1

是的，这是可能的

%# define some parameters
backgroundColor = 'r';
backgroundWidth = 0.9;
foregroundWidth = 0.3;

%# collect the data
graph = [2 3 5 4 9 1 7];
color = [0 2 2 1 0 1 2];

x = 0:length(graph)-1;
colIdx = color>1;
bgBarHeight = max(graph)+1; %# background bars are 1 taller than max

%# first, plot red bars - I plot them as background as in your question, 
%# not as transparent overlay as in your example (see yuk's answer for that)
bar(x,colIdx*bgBarHeight,backgroundWidth,'FaceColor',backgroundColor,'EdgeColor','none')

%# use hold on to prevent background from disappearing
hold on

%# then, plot foreground bars. Use hold on so that the background isn't lost
bar(x,graph,foregroundWidth,'FaceColor','k')

%# label the axes
xlabel('X Axis')
ylabel('Y Axis')

Answer 2

稍微修改 Jonas 代码，使背景栏透明并纠正一些错误：

%# define some parameters
foregroundColor = 'k';
backgroundColor = 'r';
foregroundWidth = 0.3;
backgroundWidth = 0.9;

%# collect the data
graph = [2 3 5 4 9 1 7];
color = [0 2 2 1 0 1 2];

x = 0:length(graph)-1;
colIdx = color>1;
bgBarHeight = max(graph)+1; %# background bars are 1 taller than max

%# first, plot foreground bars
b1 = bar(x,graph,foregroundWidth,'FaceColor',foregroundColor);
hold on
%# then, plot background bars. 
%# they will overlap foreground bars, but we'll make them transparent later
b2 = bar(x,colIdx*bgBarHeight,backgroundWidth,'FaceColor',backgroundColor,'EdgeColor','none');
hold off

%# make background bars transparent
pch = get(b2,'child'); %# get patch objects from barseries object
set(pch,'FaceAlpha',0.3); %# set transparency

xlabel('X Axis')
ylabel('Y Axis')