# Feature scaling Techniques for Machine learning in Python:

### Why is scaling needed in Machine learning?

The numerical features can be of different range. If the difference between the features is larger, the machine learning model may produce poor results. In order to overcome this, data is transformed by using feature scaling methods to fit into a particular range.

### Feature scaling Techniques:

• Standardization

• Min-Max Scaling

• Absolute Maximum Scaling

• Robust Scaling

### 1) Standardization

In this method Z value is calculated by the below formula for each and every data and it is replaced with the new value.

X new = (X-X mean)/Ïƒ

#### Importing libraries:

#### Loading dataset:

#### Shape of the dataset:

#### Splitting dependent and independent variable:

#### Splitting test and train dataset:

#### X_train before scaling:

#### Fit and transform using StandardScaler from sklearn:

Test and train input data is scaled separately.

#### Scaled test data:

#### Building a Linear regression model after standardization:

### 2) Min-Max Scaling:

X new= (X-X min)/ (X max-X min)

In Min-Max scaling method new value is calculated by subtracting each value from the dataset with the minimum value and then it is subtracted by the difference of the maximum and minimum value. All the new values lie in between 0 and 1.

#### Fit and transform using MinMaxScaler from sklearn:

#### Scaled test data:

In this method each value in the column is divided by the maximum value of that particular column. Here the new values lie between -1 to 1.

#### Fit and transform using MaxAbsScaler from sklearn:

### 4) Robust Scaling

New value is calculated by subtracting each value with the median value and divided by the Inter Quantile Range (IQR). It is the difference between 75th percentile and 25th percentile.

X new = (X-X median)/IQR

Unlike the other scaling methods, it is robust to the outliers.

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