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Python Strings Tutorial: Slicing, f-strings and String Methods with Examples

P3.3 Python String Methods: strip, lower, upper, replace, split

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Why. Users type " mumbai", "MUMBAI " and "Mumbai". To a computer these are three different cities. Cleaning methods make them the same.

What. A method is a function attached to a value. You call it with a dot: text.lower().

Method What it does Example Result
strip() removes spaces at both ends " Pune ".strip() "Pune"
lower() all small letters "PUNE".lower() "pune"
upper() all capital letters "pune".upper() "PUNE"
title() first letter of each word capital "new york".title() "New York"
replace(a, b) changes a into b "1,200".replace(",", "") "1200"
split(sep) cuts into a list "a,b".split(",") ["a", "b"]

How to read this table: each row is one method with a small input and the result it gives.

How.

Clean a messy city name

  1. Remove outer spaces with strip().
  2. Fix the case with title().
  3. Compare or store the clean value.

Worked example A — Clean spaces and case.

Step 1 — What we do. A form for a bank in Chennai collected the city with extra spaces and capital letters.

Step 2 — Type and run this code.

city = "   CHENNAI  "
clean = city.strip().title()
print(clean)

Step 3 — Output you should see.

Chennai

Step 4 — What it means. Methods can be chained: first strip(), then title(). Result: "Chennai".

Worked example B — Clean a money value.

Step 1 — What we do. An invoice from Johannesburg has the amount "R 12,450.00". We remove the symbol and comma.

Step 2 — Type and run this code.

raw = "R 12,450.00"
num = float(raw.replace("R", "").replace(",", "").strip())
print(num)

Step 3 — Output you should see.

12450.0

Step 4 — What it means. After cleaning, the text becomes the number 12450.0, ready for maths.

Worked example C — Split a full name and an email.

Step 1 — What we do. We split a full name into parts and take the domain from an email.

Step 2 — Type and run this code.

full = "Sofia Garcia Lopez"
parts = full.split(" ")
print(parts)
print(parts[0])
email = "sofia@example.com"
print(email.split("@")[1])

Step 3 — Output you should see.

['Sofia', 'Garcia', 'Lopez']
Sofia
example.com

Step 4 — What it means. split(" ") cuts at each space and gives a list. [0] takes the first item. The same idea finds email domains.

Worked example D — Join a list back into text.

Step 1 — What we do. We join a list of product tags into one line with commas.

Step 2 — Type and run this code.

tags = ["organic", "fresh", "local"]
print(", ".join(tags))

Step 3 — Output you should see.

organic, fresh, local

Step 4 — What it means. join is the opposite of split. The text before .join is put between items.

Ravindra Bagale's Tip

Strings never change in place. city.strip() gives a new string; write city = city.strip() to keep it.