How to Split a List of Tuples into Two Separate Lists in Python – 4 Easy Methods

Hello, I’m a Python enthusiast. Yesterday a fan asked how to split a list of tuples into two separate lists.

Original list:

[("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3), ("c", 1), ("c", 2), ("c", 3)]

Goal: separate the letters and numbers into two lists.

Implementation Process

Method One – Simple Loop

Use a straightforward loop to append each element to its own list.

# coding:utf-8
# @Time : 2022/5/6 11:46
# @Author: PiPi
letter_list = []
num_list = []
list1 = [("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3), ("c", 1), ("c", 2), ("c", 3)]
for i in list1:
    letter_list.append(i[0])
    num_list.append(i[1])
print(letter_list)
print(num_list)

Method Two – Zip Unpacking

Leverage zip to unpack the list in one line.

list1 = [("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3), ("c", 1), ("c", 2), ("c", 3)]
list_result = tuple(zip(*list1))
letter_list = list(list_result[0])
num_list = list(list_result[1])
print(letter_list)
print(num_list)

A more concise form:

letter_list, num_list = zip(*list1)
print(letter_list)
print(num_list)

Method Three – Using pandas

Convert the list to a DataFrame and extract columns.

import pandas as pd
list1 = [("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3), ("c", 1), ("c", 2), ("c", 3)]
df = pd.DataFrame(list1)
print(df[0].tolist())
print(df[1].tolist())

Method Four – Using numpy

Transform the list to a NumPy array and transpose.

import numpy as np
list1 = [("a", 1), ("a", 2), ("a", 3), ("b", 1), ("b", 2), ("b", 3), ("c", 1), ("c", 2), ("c", 3)]
letter_list, num_list = np.array(list1).T.tolist()
print(letter_list)
print(num_list)

Summary

We presented four ways to split a list of tuples into two separate lists in Python. All methods achieve the same result, and you can choose the one that best fits your workflow or library preferences.