MATLAB Examples

# Common Indexing and Searching Methods

This example shows several indexing and searching methods for categorical arrays.

```load hospital; size(hospital) ```
```ans = 100 7 ```

The dataset array has 100 observations and 7 variables.

Index a variable by name. Return the minimum age in the dataset array.

```min(hospital.Age) ```
```ans = 25 ```

Delete the variable Trials.

```hospital.Trials = []; size(hospital) ```
```ans = 100 6 ```

Index an observation by name. Display measurements on the first five variables for the observation named PUE-347.

```hospital('PUE-347',1:5) ```
```ans = LastName Sex Age Weight Smoker PUE-347 'YOUNG' Female 25 114 false ```

Index variables by number. Create a new dataset array containing the first four variables of hospital.

```dsNew = hospital(:,1:4); dsNew.Properties.VarNames(:) ```
```ans = 4x1 cell array {'LastName'} {'Sex' } {'Age' } {'Weight' } ```

Index observations by number. Delete the last 10 observations.

```hospital(end-9:end,:) = []; size(hospital) ```
```ans = 90 6 ```

Search for observations by logical condition. Create a new dataset array containing only females who smoke.

```dsFS = hospital(hospital.Sex=='Female' & hospital.Smoker==true,:); dsFS(:,{'LastName','Sex','Smoker'}) ```
```ans = LastName Sex Smoker LPD-746 'MILLER' Female true XBR-291 'GARCIA' Female true AAX-056 'LEE' Female true DTT-578 'WALKER' Female true AFK-336 'WRIGHT' Female true RBA-579 'SANCHEZ' Female true HAK-381 'MORRIS' Female true NSK-403 'RAMIREZ' Female true ILS-109 'WATSON' Female true JDR-456 'SANDERS' Female true HWZ-321 'PATTERSON' Female true GGU-691 'HUGHES' Female true WUS-105 'FLORES' Female true ```