Box Plot with Percentiles Known

I want to plot accuracy measures for an environmental variable, using the box plot approach. I have the error values / bounds for the 5, 25, 75, and 95th percentiles. All I want to do is show these error bounds using a box plot. I don't want box plot to calculate anything ... just produce the plot. Is there some way to do this in MATLAB ??

[bym]

I don't suppose errorbar() helps you?

[Laurens Bakker]

I've searched for this as well, without success...

Answer 1

[Oleg Komarov]

One approach is to draw the boxplot and then adjust it:

Say you have data

data = rand(100,2);

% Your 5 (1st row), 25, 75, 95 (last row) stats

s    = [0.3 0.2; 0.4 0.42; 0.8 0.79; .89 .88];

% Calculate boxplot retaining handles

h    = boxplot(data);

% Modify upper whisker's length

set(h(1,:),{'Ydata'},num2cell(s(end-1:end,:),1)')

% Modify lower whisker's length

set(h(2,:),{'Ydata'},num2cell(s(2:-1:1,:),1)')

% Modify upper whisker's endbar

set(h(3,:),{'Ydata'},num2cell(s([end end],:),1)')

% Modify lower whisker's endbar

set(h(4,:),{'Ydata'},num2cell(s([1 1],:),1)')

% Modify body

set(h(5,:),{'Ydata'},num2cell(s([2 3 3 2 2],:),1)')

% Median? (nothing specified, just invisible)

set(h(6,:),{'Visible'},{'off'})

% Outliers? (set the old ones to off and draw new ones)

set(h(7,:),{'Visible'},{'off'})
hold on
plot(1,.95,'+r',2,.1,'+r')

You could encapsulate these commands in a function or you could write a personalized boxplot, which way is best depends on the use you need of it.