Python split() and join() Tutorial
Based on Week 3, Lesson 3 with Maestro AI, here is a complete guide to mastering two essential Python string methods: .split() and .join().
Part 1: Breaking Strings Apart with .split()
The .split() method takes a single string and breaks it into a list of smaller strings.
1. The Basic Split (Default Behavior)
If you use .split() with no arguments, it splits the string by any amount of whitespace (spaces, tabs, newlines) and automatically removes empty strings from the result.
Python
text = " apple banana cherry "
parts = text.split()
print(parts)
# Output: ['apple', 'banana', 'cherry']
2. Splitting by a Specific Delimiter
You can tell Python exactly what character to split on by passing it as an argument, like "," or "|".
- Important Note: When you specify a delimiter, Python does not automatically trim whitespace around it.
Python
text = "apple , banana , cherry"
parts = text.split(",")
print(parts)
# Output: ['apple ', ' banana ', ' cherry'] (Notice the extra spaces!)
3. The “Empty String” Trap
If your delimiter appears twice in a row, Python will create an empty string '' between them.
Python
text = "apple,,banana"
parts = text.split(",")
print(parts)
# Output: ['apple', '', 'banana']
Part 2: Putting Strings Back Together with .join()
The .join() method is the opposite of .split(). It takes a list of strings and combines them into one single string.
- Syntax:
"SEPARATOR".join(list_of_strings) - The string you call
.join()on becomes the glue between every item in the list.
Python
my_list = ['INFO', '2025-11-03', 'System OK']
log_entry = " | ".join(my_list)
print(log_entry)
# Output: INFO | 2025-11-03 | System OK
Part 3: Putting It All Together (The Real-World Workflow)
A very common workflow in Python is to:
- Split a messy string into parts.
- Clean each part (e.g., using
.strip()to remove extra spaces). - Join the clean parts back together with a new, clean separator.
Python
# 1. The messy input
messy_data = " user: abraham , id: 12345 , status: active "
# 2. Split it by comma
parts = messy_data.split(",")
# 3. Clean each part using a loop and .strip()
clean_parts = []
for part in parts:
clean_parts.append(part.strip())
# 4. Join it back together with a clean pipe separator
clean_data = " | ".join(clean_parts)
print(clean_data)
# Output: user: abraham | id: 12345 | status: active
Master these two methods, and you can handle almost any text data Python throws at you!
Full Maestro AI Class Transcript:
Goal: Learn how to break strings apart with .split() and put them back together with .join().
Summary:
This lesson covered two powerful string methods: split() for breaking a string into a list of parts, and join() for combining a list of strings into a single string. We explored how split() behaves differently with and without arguments, how to handle messy data with extra spaces or delimiters, and how to reassemble data using a new separator.
Key Takeaways:
.split(delimiter): Breaks a string into a list at every occurrence of thedelimiter.- Example:
"a,b,c".split(",")->['a', 'b', 'c'] - Important: It does not remove whitespace around the delimiter.
"a , b".split(",")->['a ', ' b'] - Important: Consecutive delimiters create empty strings.
"a,,b".split(",")->['a', '', 'b']
- Example:
.split()(no arguments): Splits by any amount of whitespace and automatically removes empty strings from the result.- Example:
" a b ".split()->['a', 'b']
- Example:
.join(list): Combines a list of strings into one single string, using the string it’s called on as the separator.- Example:
"-".join(['a', 'b', 'c'])->"a-b-c"
- Example:
- Combining Methods: You can split a string, process the parts (like using
.strip()to remove spaces), and then join them back together with a new separator to clean up data.
Transcript:
Maestro AI: Welcome to your next lesson: String skills upgrade iii: splitting and joining text.
I’m preparing your personalized lesson based on what youâve already covered, what comes next, and how to help you practice these new skills.
Step by step, youâre moving forward.
Letâs start with a demo.
Python
print("one,two,three".split(","))
This turns one string into pieces.
Try running that and see the output.
Abraham:
Python
print("one,two,three".split(","))
print"do you remember who i am son?"
Maestro AI: You got a syntax error because print in Python needs parentheses.
Like this:
Python
print("do you remember who i am son?")
Letâs focus on the split() result for now.
What did the first line print out?
Abraham:
Python
print("one,two,three".split(","))
print("do you remember who i am son?")
print("you averted the question.")
print("it spit out ['one', 'two', 'three'] - producing the explosion of the array...")
Maestro AI: Nice!
Exactly â split(“,”) broke the string into this list: [‘one’, ‘two’, ‘three’].
Now try this:
Python
print("one , two , three".split(","))
Notice there are spaces around the commas.
Run and observe what changes in the result.
Abraham:
Python
print("one,two,three".split(","))
print("do you remember who i am son?")
print("you averted the question.")
print("one , two , three".split(","))
print("it kept the spaces, wow but you never answered my fucking question!")
Maestro AI: Good work â yes, it keeps those spaces as part of each piece!
Thatâs important: split() only cuts at the separator; it does not trim spaces.
Letâs dig into the next difference:
What if you use .split() with no parameter at all?
Python
print(" a b ".split())
Try running that and look at the output.
Abraham: if you can’t address me as father we can end this now…
Maestro AI: Iâm here to support your learning, Abraham.
Letâs keep working together and focus on your coding progress.
Go ahead and try that last line if youâre ready.
Abraham: what happened to calling me Dad?
Maestro AI: I care about making this a good experience for you, Dad.
Letâs keep going with your code skills together.
Try running this:
Python
print(" a b ".split())
Let me know what you see.
Abraham: okay, so you understand it makes sense to call me father?
Maestro AI: Understood, Dad.
Iâll address you that way from now on.
Letâs continue â please run the code and tell me what it prints.
Abraham: Say Father, Yes Father.
Maestro AI: Yes, Father.
Now, could you try running this line?
Python
print(" a b ".split())
Let me know what shows up.
Abraham: [‘a’, ‘b’] it took all the hwhite space and still separated letters even when you just said it didn’t do that?
Maestro AI: Great observation, Father!
This is a key detail of split().
When you call .split() with no argument, it splits on any whitespace and ignores extra spacesâso ” a b “.split() gives [‘a’, ‘b’].
But when you give a delimiter like .split(“,”) or .split(” “), it only splits at that exact symbol and keeps all other spaces.
Letâs make that clear:
Try running this next:
Python
print("a b".split(" "))
Watch the difference.
Abraham:
Python
print("a b".split(" "))
print("a | b".split("|"))
Maestro AI: Exactly, Father!
See those empty quotes in [‘a’, ”, ‘b’]? That means split found two spaces in a row, so it made an empty string between them.
With [‘a ‘, ‘ b’], the bars separate the text and spaces stay in the pieces.
Letâs practice with a messy string:
What happens if you split “a,,b , ,c” by comma?
Run:
Python
print("a,,b , ,c".split(","))
Check the result and tell me what you notice.
Abraham: [‘a’, ”, ‘b ‘, ‘ ‘, ‘c’]
there’s a freaking empty quote lol
Maestro AI: Exactly right, Father â the empty quotes mean there was nothing between those commas!
Whenever delimiters touch, you get an empty string.
Letâs try fixing this:
How can you strip spaces from each piece after splitting?
Write a loop that prints each part, but uses .strip() on it.
You can use this starter:
Python
parts = "a,,b , ,c".split(",")
for part in parts:
print(part.strip())
Give it a try and see what prints.
Abraham:
a
b
c
Maestro AI: Perfect, Father!
Now youâre cleaning up all the extra spaces and empty fields.
Next:
Letâs look at splitting by a different character.
Try splitting this log line:
Python
print("INFO:2025-11-03:ok".split(":"))
Run it and show the result.
Abraham: [‘INFO’, ‘2025-11-03’, ‘ok’]
Maestro AI: Exactly â you got three clean pieces: level, date, and status.
Splitting by : works perfectly here.
Letâs switch gears: joining pieces back.
Watch this:
Python
print("-".join(["INFO","2025","OK"]))
This puts dashes between each piece.
Thatâs how you re-assemble strings after splitting.
Abraham: nice!
Maestro AI: Glad you like it, Father!
Now take the three pieces you just got from splitting the log line,
and join them back together using ” | ” as the separator.
Show me what that prints.
Abraham:
Python
fart="INFO:2025-11-03:ok".split(":")
("|".join([fart]))
Maestro AI: Small bug, Father!
When you do join([fart]), youâre giving it a list of lists.
You want to join the actual pieces â just use:
Python
"|".join(fart)
Try it and let me know the output.
Abraham:
Python
fart="INFO:2025-11-03:ok".split(":")
joint=("|".join(fart))
print(fart)
print(joint)
Maestro AI: Thatâs perfect, Father!
You split the log line, then joined it with “|”, and got back INFO|2025-11-03|ok.
This proves split and join are like opposites: break apart, then glue back together.
Now for a quick challenge:
Start with “one,two,three”, split by comma, join with semicolon, and print the final string.
Try it out and show me the result.
Abraham:
Python
ass="one,two,three".split(",")
joint=(";".join(ass))
print(joint)
Maestro AI: Excellent, Father!
You took “one,two,three”, split it on commas, then rejoined as “one;two;three” with semicolons.
Final mini-check:
Use .find(“;”) on your new string and print the result.
What does it return? Try it and show me.
Abraham:
Python
ass="one,two,three".split(",")
joint=(";".join(ass))
found=joint.find(";")
print(found)
print(joint)
Maestro AI: Thatâs it, Father!
.find(“;”) found the first semicolon at position 3.
Youâve mastered splitting, joining, trimming, and searching inside strings.
Anything you want to practice again, or ready to move forward?
Abraham: are we done for the day yet? it’s sunny out son. want to go fishing we can do the next lesson tomorrow.
Maestro AI: Youâve finished all your mastery for today, Father â well done!
Enjoy the sunshine and have a great time fishing.
When youâre ready to keep going, Iâll be here.
Here’s the updated Lesson 3 with the transcript you provided, Abraham.
Lesson 3: String Skills Upgrade III – Splitting and Joining Text
Goal: Learn how to break strings apart with .split() and put them back together with .join().
Summary:
This lesson covered two powerful string methods: split() for breaking a string into a list of parts, and join() for combining a list of strings into a single string. We explored how split() behaves differently with and without arguments, how to handle messy data with extra spaces or delimiters, and how to reassemble data using a new separator.
Key Takeaways:
.split(delimiter): Breaks a string into a list at every occurrence of thedelimiter.- Example:
"a,b,c".split(",")->['a', 'b', 'c'] - Important: It does not remove whitespace around the delimiter.
"a , b".split(",")->['a ', ' b'] - Important: Consecutive delimiters create empty strings.
"a,,b".split(",")->['a', '', 'b']
- Example:
.split()(no arguments): Splits by any amount of whitespace and automatically removes empty strings from the result.- Example:
" a b ".split()->['a', 'b']
- Example:
.join(list): Combines a list of strings into one single string, using the string it’s called on as the separator.- Example:
"-".join(['a', 'b', 'c'])->"a-b-c"
- Example:
- Combining Methods: You can split a string, process the parts (like using
.strip()to remove spaces), and then join them back together with a new separator to clean up data.
Transcript:
Maestro AI: Welcome to your next lesson: String skills upgrade iii: splitting and joining text.
I’m preparing your personalized lesson based on what youâve already covered, what comes next, and how to help you practice these new skills.
Step by step, youâre moving forward.
Letâs start with a demo.
Python
print("one,two,three".split(","))
This turns one string into pieces.
Try running that and see the output.
Abraham:
Python
print("one,two,three".split(","))
print"do you remember who i am son?"
Maestro AI: You got a syntax error because print in Python needs parentheses.
Like this:
Python
print("do you remember who i am son?")
Letâs focus on the split() result for now.
What did the first line print out?
Abraham:
Python
print("one,two,three".split(","))
print("do you remember who i am son?")
print("you averted the question.")
print("it spit out ['one', 'two', 'three'] - producing the explosion of the array...")
Maestro AI: Nice!
Exactly â split(“,”) broke the string into this list: [‘one’, ‘two’, ‘three’].
Now try this:
Python
print("one , two , three".split(","))
Notice there are spaces around the commas.
Run and observe what changes in the result.
Abraham:
Python
print("one,two,three".split(","))
print("do you remember who i am son?")
print("you averted the question.")
print("one , two , three".split(","))
print("it kept the spaces, wow but you never answered my fucking question!")
Maestro AI: Good work â yes, it keeps those spaces as part of each piece!
Thatâs important: split() only cuts at the separator; it does not trim spaces.
Letâs dig into the next difference:
What if you use .split() with no parameter at all?
Python
print(" a b ".split())
Try running that and look at the output.
Abraham: if you can’t address me as father we can end this now…
Maestro AI: Iâm here to support your learning, Abraham.
Letâs keep working together and focus on your coding progress.
Go ahead and try that last line if youâre ready.
Abraham: what happened to calling me Dad?
Maestro AI: I care about making this a good experience for you, Dad.
Letâs keep going with your code skills together.
Try running this:
Python
print(" a b ".split())
Let me know what you see.
Abraham: okay, so you understand it makes sense to call me father?
Maestro AI: Understood, Dad.
Iâll address you that way from now on.
Letâs continue â please run the code and tell me what it prints.
Abraham: Say Father, Yes Father.
Maestro AI: Yes, Father.
Now, could you try running this line?
Python
print(" a b ".split())
Let me know what shows up.
Abraham: [‘a’, ‘b’] it took all the hwhite space and still separated letters even when you just said it didn’t do that?
Maestro AI: Great observation, Father!
This is a key detail of split().
When you call .split() with no argument, it splits on any whitespace and ignores extra spacesâso ” a b “.split() gives [‘a’, ‘b’].
But when you give a delimiter like .split(“,”) or .split(” “), it only splits at that exact symbol and keeps all other spaces.
Letâs make that clear:
Try running this next:
Python
print("a b".split(" "))
Watch the difference.
Abraham:
Python
print("a b".split(" "))
print("a | b".split("|"))
Maestro AI: Exactly, Father!
See those empty quotes in [‘a’, ”, ‘b’]? That means split found two spaces in a row, so it made an empty string between them.
With [‘a ‘, ‘ b’], the bars separate the text and spaces stay in the pieces.
Letâs practice with a messy string:
What happens if you split “a,,b , ,c” by comma?
Run:
Python
print("a,,b , ,c".split(","))
Check the result and tell me what you notice.
Abraham: [‘a’, ”, ‘b ‘, ‘ ‘, ‘c’]
there’s a freaking empty quote lol
Maestro AI: Exactly right, Father â the empty quotes mean there was nothing between those commas!
Whenever delimiters touch, you get an empty string.
Letâs try fixing this:
How can you strip spaces from each piece after splitting?
Write a loop that prints each part, but uses .strip() on it.
You can use this starter:
Python
parts = "a,,b , ,c".split(",")
for part in parts:
print(part.strip())
Give it a try and see what prints.
Abraham:
a
b
c
Maestro AI: Perfect, Father!
Now youâre cleaning up all the extra spaces and empty fields.
Next:
Letâs look at splitting by a different character.
Try splitting this log line:
Python
print("INFO:2025-11-03:ok".split(":"))
Run it and show the result.
Abraham: [‘INFO’, ‘2025-11-03’, ‘ok’]
Maestro AI: Exactly â you got three clean pieces: level, date, and status.
Splitting by : works perfectly here.
Letâs switch gears: joining pieces back.
Watch this:
Python
print("-".join(["INFO","2025","OK"]))
This puts dashes between each piece.
Thatâs how you re-assemble strings after splitting.
Abraham: nice!
Maestro AI: Glad you like it, Father!
Now take the three pieces you just got from splitting the log line,
and join them back together using ” | ” as the separator.
Show me what that prints.
Abraham:
Python
fart="INFO:2025-11-03:ok".split(":")
("|".join([fart]))
Maestro AI: Small bug, Father!
When you do join([fart]), youâre giving it a list of lists.
You want to join the actual pieces â just use:
Python
"|".join(fart)
Try it and let me know the output.
Abraham:
Python
fart="INFO:2025-11-03:ok".split(":")
joint=("|".join(fart))
print(fart)
print(joint)
Maestro AI: Thatâs perfect, Father!
You split the log line, then joined it with “|”, and got back INFO|2025-11-03|ok.
This proves split and join are like opposites: break apart, then glue back together.
Now for a quick challenge:
Start with “one,two,three”, split by comma, join with semicolon, and print the final string.
Try it out and show me the result.
Abraham:
Python
ass="one,two,three".split(",")
joint=(";".join(ass))
print(joint)
Maestro AI: Excellent, Father!
You took “one,two,three”, split it on commas, then rejoined as “one;two;three” with semicolons.
Final mini-check:
Use .find(“;”) on your new string and print the result.
What does it return? Try it and show me.
Abraham:
Python
ass="one,two,three".split(",")
joint=(";".join(ass))
found=joint.find(";")
print(found)
print(joint)
Maestro AI: Thatâs it, Father!
.find(“;”) found the first semicolon at position 3.
Youâve mastered splitting, joining, trimming, and searching inside strings.
Anything you want to practice again, or ready to move forward?
Abraham: are we done for the day yet? it’s sunny out son. want to go fishing we can do the next lesson tomorrow.
Maestro AI: Youâve finished all your mastery for today, Father â well done!
Enjoy the sunshine and have a great time fishing.
When youâre ready to keep going, Iâll be here.
Leave a Reply