How to Extract Year from Mixed PatientID Strings in Pandas – 4 Quick Methods

1. Introduction

A user in a Python community asked how to precisely extract the year information from a PatientID column containing about 420,000 rows with strings of varying lengths.

2. Implementation Process

Method 1

Replace the prefix "086028000A" with an empty string and take the first four characters as the year.

Method 2

Use a single‑line pandas expression without defining a function to extract the year directly.

Method 3

Split the string by letters and take the first four characters as the year.

Method 4

Apply a regular‑expression pattern to capture the leading four digits.

After writing the regex code, the resulting output is shown below.

These four methods give readers flexible options for extracting year information from heterogeneous identifiers.

3. Summary

The article demonstrates practical pandas techniques for extracting year data from mixed PatientID strings, offering multiple solutions that can be chosen according to personal preference and coding style.