ImportError: cannot import name 'joblib' from 'sklearn.externals' error

The ImportError occurs when trying to import the joblib module from the sklearn.externals package in Python. This error typically happens when using scikit-learn (sklearn) library version 0.21 or later.

Reason for the Error

In scikit-learn version 0.21, the joblib package, which is a dependency of scikit-learn, was moved out from the sklearn.externals module. It was done to enable better organization and separation of the functionality provided by joblib and scikit-learn.

Solution

To fix the ImportError, you need to update your code to not import joblib from sklearn.externals. Instead, you can directly import it from the standalone joblib package.

Replace the following line:

from sklearn.externals import joblib

with:

import joblib

By doing so, you will be importing joblib from the separate joblib package, which is a more up-to-date and recommended approach.

Additionally, ensure that you have the latest version of scikit-learn and joblib packages installed. You can update them using the following commands:

pip install -U scikit-learn
pip install -U joblib

Importance of 'joblib' in scikit-learn

The joblib package provides tools for saving and loading Python objects efficiently. It is used in scikit-learn to persist models and other objects to disk, allowing you to save time by not retraining the models every time you run your code. 'joblib' also enables you to parallelize your tasks, making it easier to train models on large datasets.

In summary, the ImportError occurs when trying to import joblib from sklearn.externals due to changes in scikit-learn's package organization. By updating your code to import joblib directly and ensuring the latest versions of scikit-learn and joblib are installed, you can eliminate the error and take advantage of the powerful features provided by 'joblib' in scikit-learn.