# Librairies
```python
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns
import sklearn
print("sklearn version :", sklearn.__version__)
```
sklearn version : 1.5.1
# Introduction aux trannsformers
```python
from sklearn.preprocessing import LabelEncoder
```
```python
X = np.array(["chien", "chien", "chat", "oiseau"])
```
```python
encoder = LabelEncoder()
encoder.fit(X)
encoder.transform(X)
```
array([1, 1, 0, 2])
```python
X_new = np.array(["oiseau", "oiseau", "chien"])
# Attention ne pas réentrainer le label encoder avec la méthode fit sinon on change les règles de transformation
encoder.transform(X_new)
```
array([2, 2, 1])