# In this tutorial, we will try to answer the following questions;

- What are the Apriori candidate’s generations?
- What is self-joining?
- what is the Apriori pruning principle?

## Apriori Candidates generation:

Candidates can be generated by the self joining and Apriori pruning principles.

**Step 1: **

**self-joining**

## Example of self-joining

V W X Y Z*X=*{V W X*, V W Y**, V X Y**, V X Z, W X Y*}Self-joining = *X *** X**V W X Y* from V W *X* and V W *Y**V X Y Z* from V X *Y* and V X *Z*

So frequent candidates are ** V W X Y** and

*V X Y Z***Step 2: **

**Apriori pruning principle:**

## Example of Apriori pruning principle

V W X Y Z*X=*{V W X*, V W Y**, V X Y**, V X Z, W X Y*} *According to Apriori Pruning principle V X Y Z* is removed because V Y *Z* is not in *X. *

So frequent candidate is **V W X Y**

## Apriori Candidates generation

Candidates can be generated by the self joining and Apriori pruning principles.

**Step 1: **

### Self-joining of Apriori Candidates

#### Example of self-joining

A1 B1 C1 D1 E1

*C1=*{A1 B1 C1*, A1 B1 D1, A1 C1 D1, A1 C1 E1, B1 C1 D1*}

Self-joining = *C1 * C1A1 B1 C1 D1* from A1 B1 *C1* and A1 B1 *D1A1 C1 D1 E1* from A1 C1 *D1* and A1 C1 *E1*

So frequent candidates are *A1** **B1**C1*** D1** and

*A1*

*C1*

*D1*

*E1***Step 2: **

### Apriori pruning principle

#### Example of Apriori pruning principle

A1 B1 C1 D1 E1*C1=*{A1 B1 C1*, A1 B1 D1, A1 C1 D1, A1 C1 E1, B1 C1 D1*} *According to Apriori Pruning principle A1 C1 D1 E1* is remoA1ed because A1 D1 *E1* is not in *C1. *

So frequent candidate is **A1** **B1** **C1** **D1.**

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