str.partition()

str.partition(sep)

The .partition() method splits a string into three parts using a separator. It returns a tuple containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, the tuple contains the original string followed by two empty strings.

Syntax

str.partition(sep)

Parameters

Parameter	Type	Default	Description
sep	str	—	The separator string to split on

Return Value

Returns a tuple of three strings: (before_sep, sep, after_sep). If the separator is not found, returns (original_string, ”, ”).

Examples

Basic usage

text = "hello world"
result = text.partition(" ")
print(result)
# ('hello', 'world')

The separator is included in the result as the middle element.

Separator not found

text = "hello"
result = text.partition(" ")
print(result)
# ('hello', '', '')

When the separator doesn’t exist, the entire string becomes the first element.

Using with delimiters

url = "user@example.com"
result = url.partition("@")
print(result)
# ('user', '@', 'example.com')

This is useful for parsing email addresses or similar delimited data.

Extracting parts

timestamp = "2024-01-15"
date, sep, time = timestamp.partition("-")
print(date)
# 2024
print(time)
# 01-15

You can unpack the result directly into three variables.

Common Patterns

Safe parsing with fallback

def extract_domain(email):
    user, sep, domain = email.partition("@")
    if sep:
        return domain
    return "No domain"

print(extract_domain("user@example.com"))
# example.com
print(extract_domain("invalid"))
# No domain

This pattern avoids exceptions when the separator doesn’t exist.

Conditional processing

def process_input(value):
    key, sep, val = value.partition("=")
    if sep:
        return {key: val}
    return {"data": value}

print(process_input("name=Alice"))
# {'name': 'Alice'}
print(process_input("novalue"))
# {'data': 'novalue'}

Header parsing

header = "Content-Type: application/json"
name, sep, value = header.partition(": ")
print(name)
# Content-Type
print(value)
# application/json

Works well for parsing HTTP-style headers.

Difference from split()

The .partition() method always returns exactly three elements, making it useful when you need predictable unpacking. The .split() method returns a list of varying length:

# partition always returns 3 elements
"a-b-c".partition("-")
# ('a', '-', 'b-c')

# split returns list of varying length
"a-b-c".split("-")
# ['a', 'b', 'c']

"a b c".split(" ")
# ['a', 'b', 'c']

See Also

• str.split()
• str.rsplit()
• str.splitlines()