Introduction to list-differ

The list-differ library is a powerful tool for comparing lists in Python. It provides a suite of intuitive and flexible APIs that allow you to find differences, similarities, and changes between two lists. This comprehensive guide will cover the various APIs offered by list-differ and demonstrate their usage with code examples.

Getting Started

First, you need to install the list-differ library. You can do this using pip:

  pip install list-differ

API Overview

diff

The diff function compares two lists and returns a dictionary with added, removed, and common elements.

  from list_differ import diff
  
  list1 = [1, 2, 3, 4]
  list2 = [3, 4, 5, 6]
  
  differences = diff(list1, list2)
  print(differences)
  # Output: {'added': [5, 6], 'removed': [1, 2], 'common': [3, 4]}

added

The added function returns elements that are in the second list but not in the first.

  from list_differ import added
  
  list1 = [1, 2, 3]
  list2 = [2, 3, 4]
  
  added_elements = added(list1, list2)
  print(added_elements)
  # Output: [4]

removed

The removed function returns elements that are in the first list but not in the second.

  from list_differ import removed
  
  list1 = [1, 2, 3]
  list2 = [2, 3, 4]
  
  removed_elements = removed(list1, list2)
  print(removed_elements)
  # Output: [1]

common

The common function returns elements that are present in both lists.

  from list_differ import common
  
  list1 = [1, 2, 3]
  list2 = [2, 3, 4]
  
  common_elements = common(list1, list2)
  print(common_elements)
  # Output: [2, 3]

compare

The compare function returns a detailed comparison report between two lists, indicating the index and nature of the difference.

  from list_differ import compare
  
  list1 = [1, 2, 3, 4]
  list2 = [1, 3, 4, 5]
  
  comparison = compare(list1, list2)
  print(comparison)
  # Output: {'added': [5], 'removed': [2], 'changed': [(3, 3), (4, 5)]}

Application Example

Let’s create an application that takes two lists of student names and shows the names that have been added, removed, and have remained the same.

  from list_differ import diff
  
  previous_students = ["Alice", "Bob", "Charlie", "Diana"]
  current_students = ["Alice", "Bob", "Eve", "Frank"]

  differences = diff(previous_students, current_students)
  
  print("Added students:", differences['added'])
  # Output: Added students: ['Eve', 'Frank']
  print("Removed students:", differences['removed'])
  # Output: Removed students: ['Charlie', 'Diana']
  print("Common students:", differences['common'])
  # Output: Common students: ['Alice', 'Bob']

With these APIs, managing list comparisons and changes becomes simple and efficient.

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