MATLAB Programming Fundamentals - MathWorks

Split Data into Groups and Calculate Statistics

This example shows how to split data from the patients.mat data file into groups. Then

it shows how to calculate mean weights and body mass indices, and variances in blood

pressure readings, for the groups of patients. It also shows how to summarize the results

in a table.

Load Patient Data

Load sample data gathered from 100 patients.

load patients

Convert Gender and SelfAssessedHealthStatus to categorical arrays.

Gender = categorical(Gender);

SelfAssessedHealthStatus = categorical(SelfAssessedHealthStatus);

whos

Name Size Bytes Class Attributes

Age 100x1 800 double

Diastolic 100x1 800 double

Gender 100x1 346 categorical

Height 100x1 800 double

LastName 100x1 12416 cell

Location 100x1 15008 cell

SelfAssessedHealthStatus 100x1 592 categorical

Smoker 100x1 100 logical

Systolic 100x1 800 double

Weight 100x1 800 double

Calculate Mean Weights

Split the patients into nonsmokers and smokers using the Smoker variable. Calculate the

mean weight for each group.

[G,smoker] = findgroups(Smoker);

meanWeight = splitapply(@mean,Weight,G)

meanWeight = 2×1

149.9091

161.9412

Split Data into Groups and Calculate Statistics