Find the number of red marks in box plot

I have the box plot like this. How can I find the number of the red marks?

T = [1;-1;0.5;-0.5;0.75;-0.75;-6;-7;4;3];
h = boxplot(T,'Labels',{'1'});

Answer 1

[Chris]

One method, which may not necessarily correlate to a boxplot in all situations (but probably works for the default boxplot), is to use isoutlier:

T = [1;-1;0.5;-0.5;0.75;-0.75;-6;-7;4;3];
outliers = isoutlier(T);
numOutliers = sum(outliers)

numOutliers = 2

h = boxplot(T,'Labels',{'1'});

If you need to be sure you have the exact count in the boxplot, you can get the data in the image and drill down to find the outliers:

ax = gca;               % Get current axes
bxplt = ax.Children;    % The boxplot 
plts = bxplt.Children   % Individual plots that make up the boxplot. 

plts = 
  7×1 Line array:

  Line    (Outliers)
  Line    (Median)
  Line    (Box)
  Line    (Lower Adjacent Value)
  Line    (Upper Adjacent Value)
  Line    (Lower Whisker)
  Line    (Upper Whisker)

% plts(1) holds the outliers
numRedMarks = numel(plts(1).YData)  

numRedMarks = 2

% XData or YData -- points that make up the Outliers plot

To programmatically find the plots of outliers (in the event that you have more than one box):

idxs = find(strcmp({plts.Tag},'Outliers'));
outlierCell = {plts(idxs).YData}

outlierCell = 1×1 cell array
    {[-7 -6]}

numMarksFirstPlot = numel(outlierCell{1})

numMarksFirstPlot = 2