Vector Unit Length Scaling using sklearn

by | Nov 16, 2022 | Data Preprocessing, Machine Learning Using Python, Python Scikit-learn

In the vector unit length scaling, a feature vector is divided by the Manhattan distance (l1 norm) or by the Euclidean distance (l2 norm). We can use the Normalizer class from the sklearn.preprocessing module to perform vector unit length scaling.

Let’s look at an example. Let’s read the titanic dataset. The age column of the dataset contains the age of the passengers. We can use the following Python code to perform vector unit length scaling.

import seaborn
from sklearn.preprocessing import Normalizer

df = seaborn.load_dataset("titanic")
df.dropna(inplace=True)
normalizer = Normalizer(norm="l1")
df[["age", "fare", "pclass"]] = normalizer.fit_transform(df[["age", "fare", "pclass"]])

print(df.head())

The norm=”l1” parameter in the Normalizer() constructor indicates that l1 norm is being used to normalize each non-zero sample. Please note that we need to remove or fill in the missing values before performing vector unit length scaling. We are here using the dropna() method to drop all the rows that contain missing values in any column for simplicity.

The output of the above program will be:

    survived    pclass     sex       age  ...  deck  embark_town  alive  alone
1          1  0.009068  female  0.344567  ...     C    Cherbourg    yes  False
3          1  0.011223  female  0.392817  ...     C  Southampton    yes  False
6          0  0.009358    male  0.505322  ...     E  Southampton     no   True
10         1  0.126582  female  0.168776  ...     G  Southampton    yes  False
11         1  0.011689  female  0.677966  ...     C  Southampton    yes   True

[5 rows x 15 columns]

We can use the following Python code to use the l2 norm to normalize the data…

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Amrita Mitra

Author

Ms. Amrita Mitra is an author, who has authored the books “Cryptography And Public Key Infrastructure“, “Web Application Vulnerabilities And Prevention“, “A Guide To Cyber Security” and “Phishing: Detection, Analysis And Prevention“. She is also the founder of Asigosec Technologies, the company that owns The Security Buddy.

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