Python Strings
Create strings, use f-strings, slice text, and clean whitespace.
Why it matters: Prompts, chunks, and log lines are all strings.
Basics
Creating Strings
Use single or double quotes. Use triple quotes for multi-line text.
Prefer f-strings: f"Model {name}"
len(s) counts characters.
Strings are immutable. s.upper() returns a new string.
Common mistake: expecting s.upper() to change s in place.
Tiny example
Make a string and print its length.
name = "RAG"
print(name)
print(len(name))Basics
Slicing and Cleaning
s[0] is the first character. s[-1] is the last.
s[0:5] is the first 5 characters (end index not included).
strip() removes leading and trailing spaces.
split() breaks text into a list of words.
Common mistake: sending padded text to a model without stripping.
Tiny example
Strip spaces, then take a slice.
text = " Hello GenAI "
clean = text.strip()
print(clean)
print(clean[:5])Then AI / ML
AI / ML examples
Same idea, used in real AI work. Press Try in lab to run it.
AI / ML example
AI / ML: f-string prompt
Put variables into a prompt with curly braces.
In AI / ML: Chat apps build prompts from system text and user questions.
example.py
Python
question = "What is MLOps?"
context = "MLOps deploys and monitors models."
prompt = f"Context: {context}\nQ: {question}"
print(prompt)AI / ML example 2
AI / ML: clean user text
strip() removes extra spaces before a model call.
In AI / ML: Before RAG or chat, engineers strip and reject empty prompts.
example.py
Python
raw = " What is RAG? "
clean = raw.strip()
print(clean)
print(clean == "")Takeaways
- 1f-strings are the clean way to build text.
- 2strip() cleans spaces. len() counts characters.
- 3String methods return new strings.