Similarity Index Calculator

Formula

The formula to calculate the Similarity Index (SI) is:

\[ SI = \frac{2 \cdot C}{A + B} \]

Where:

\( SI \) is the similarity index.
\( C \) is the number of common items in both sets.
\( A \) is the total number of items in set A.
\( B \) is the total number of items in set B.

What is a Similarity Index?

The similarity index is a metric used to quantify the similarity between two sets. It is often used in various fields such as biology to measure species similarity, in information retrieval to compare documents, or in data analysis to compare sets of data. The index ranges from 0 to 1, where 0 indicates no similarity and 1 indicates identical sets.

Example Calculation

Consider an example where:

Number of Common Items (C): 5
Total Number of Items in Set A (A): 10
Total Number of Items in Set B (B): 15

Using the formula to calculate the Similarity Index:

\[ SI = \frac{2 \cdot 5}{10 + 15} = \frac{10}{25} = 0.4 \]

This means that the similarity index for this example is 0.4.