Plot Categorical Data
This example shows how to plot data from a
Load Sample Data
Load sample data gathered from 100 patients. Display the data types and sizes of the arrays from the
load patients whos
Name Size Bytes Class Attributes Age 100x1 800 double Diastolic 100x1 800 double Gender 100x1 11412 cell Height 100x1 800 double LastName 100x1 11616 cell Location 100x1 14208 cell SelfAssessedHealthStatus 100x1 11540 cell Smoker 100x1 100 logical Systolic 100x1 800 double Weight 100x1 800 double
Create Categorical Arrays
The workspace variable,
Location, lists three unique medical facilities where patients were observed.
To access and compare data more easily, convert
Location to a
Location = categorical(Location);
categorical array. The summary displays the number of times each category appears in
County General Hospital 39 St. Mary's Medical Center 24 VA Hospital 37
39 patients were observed at County General Hospital, 24 at St. Mary's Medical Center, and 37 at the VA Hospital.
The workspace variable,
SelfAssessedHealthStatus, contains four unique values,
SelfAssessedHealthStatus to an ordinal
categorical array, such that the categories have the mathematical ordering
Poor < Fair < Good < Excellent.
SelfAssessedHealthStatus = categorical(SelfAssessedHealthStatus,... ["Poor","Fair","Good","Excellent"],"Ordinal",true);
Poor 11 Fair 15 Good 40 Excellent 34
Create a histogram bar plot directly from
categorical array is an ordinal
categorical array. The categories have the ordering
Excellent, which determines the order of the categories along the x-axis of the plot. The
histogram function plots the category counts for each of the four categories.
figure histogram(SelfAssessedHealthStatus) title("Self Assessed Health Status From 100 Patients")
Create a histogram of the hospital location for only the patients who assessed their health as
figure histogram(Location(SelfAssessedHealthStatus <= "Fair")) title("Location of Patients in Fair or Poor Health")
Create Pie Chart
Create a pie chart directly from a
figure pie(SelfAssessedHealthStatus); title("Self Assessed Health Status From 100 Patients")
pie accepts the
SelfAssessedHealthStatus, and plots a pie chart of the four categories.
Create Pareto Chart
Create a Pareto chart from the category counts for each of the four categories of
figure A = countcats(SelfAssessedHealthStatus); C = categories(SelfAssessedHealthStatus); pareto(A,C); title("Self Assessed Health Status From 100 Patients")
The first input argument to
pareto must be a vector. If a
categorical array is a matrix or multidimensional array, reshape it into a vector before calling
Create Scatter Plot
Determine if self-assessed health is related to blood pressure readings. Create a scatter plot of
Systolic readings for two groups of patients.
First, create x- and y-arrays of blood pressure readings for two groups of patients. The first group of patients consists of those who assess their self-health as either
Fair. The second group consists of those who assess their self-health as
You can use the
SelfAssessedHealthStatus, to create logical indices. Use the logical indices to extract values from
Systolic into different arrays.
X1 = Diastolic(SelfAssessedHealthStatus <= "Fair"); Y1 = Systolic(SelfAssessedHealthStatus <= "Fair"); X2 = Diastolic(SelfAssessedHealthStatus >= "Good"); Y2 = Systolic(SelfAssessedHealthStatus >= "Good");
Y1 are 26-by-1 numeric arrays containing data for the patients with
Y2 are 74-by-1 numeric arrays containing data for the patients with
Create a scatter plot of blood pressure readings for the two groups of patients. The plot shows no suggestive differences between the two groups, possibly indicating that blood pressure does not affect how these patients assessed their own health.
figure h1 = scatter(X1,Y1,"o"); hold on h2 = scatter(X2,Y2,"x"); title("Blood Pressure for Groups of Patients Assessing Self Health"); xlabel("Diastolic (mm Hg)") ylabel("Systolic (mm Hg)") legend("Poor or Fair","Good or Excellent")