Searching and replacing text in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to replace all occurrences of 'cat' with 'dog' in the text.

Python

text = 'The cat sat on the cat mat.'
new_text = text.[1]('cat', 'dog')
print(new_text)

Drag options to blanks, or click blank then click option'

Areplace

Bfind

Csplit

Djoin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'find' instead of 'replace' which only finds the position.

Using 'split' or 'join' which do not replace text directly.

The replace method replaces all occurrences of a substring with another substring.

2fill in blank

medium

Complete the code to replace only the first occurrence of 'apple' with 'orange'.

Python

text = 'apple banana apple grape'
new_text = text.[1]('apple', 'orange', 1)
print(new_text)

Drag options to blanks, or click blank then click option'

Acount

Bfind

Creplace

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'find' which only locates the substring.

Using 'count' or 'index' which do not replace text.

The replace method can take a third argument to limit how many replacements happen.

3fill in blank

hard

Fix the error in the code to replace 'blue' with 'red' in the string.

Python

text = 'blue sky'
new_text = text.[1]('blue', 'red')
print(new_text)

Drag options to blanks, or click blank then click option'

Areplace

BReplace

Creplac

Dsubstitute

Attempts:

3 left

💡 Hint

Common Mistakes

Using capitalized method names like 'Replace'.

Misspelling the method name.

The correct method name is replace all lowercase. Python is case-sensitive.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their lengths as values, but only for words longer than 3 letters.

Python

words = ['apple', 'bat', 'carrot', 'dog']
lengths = {word: [1] for word in words if len(word) [2] 3}
print(lengths)

Drag options to blanks, or click blank then click option'

Alen(word)

B<=

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself instead of its length.

Using the wrong comparison operator.

Use len(word) to get the length and filter words with length greater than 3 using >.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys and their lengths as values, only for words longer than 4 letters.

Python

words = ['tree', 'house', 'car', 'elephant']
result = { [1]: [2] for w in words if len(w) [3] 4 }
print(result)

Drag options to blanks, or click blank then click option'

Aw.upper()

Blen(w)

C>

Dw

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word as key without uppercase.

Using wrong comparison operator or value.

Use w.upper() for uppercase keys, len(w) for values, and filter words longer than 4 with >.

Practice

1. What does the replace method do in Python strings?

easy

A. It finds a specified substring and replaces it with another substring.

B. It deletes a substring from the string permanently.

C. It changes the original string directly without creating a new one.

D. It counts how many times a substring appears in the string.

Solution

1. Step 1: Understand the purpose of replace()

   The replace method searches for a substring and replaces it with another substring.

2. Step 2: Check if it modifies original string

   Strings are immutable in Python, so replace returns a new string without changing the original.

3. Final Answer:

   It finds a specified substring and replaces it with another substring. -> Option A

4. Quick Check:

   replace() = find and change substring [OK]

Hint: Remember: replace returns new string, original stays same [OK]

Common Mistakes:

• Thinking replace changes the original string
• Confusing replace with delete or count methods
• Assuming replace modifies in-place

2. Which of the following is the correct syntax to replace all occurrences of 'cat' with 'dog' in a string text?

easy

A. text.replace('cat', 'dog', all=True)

B. text.replace('cat', 'dog')

C. text.replace('cat' -> 'dog')

D. text.replace('cat', 'dog', count=0)

Solution

1. Step 1: Recall replace() syntax

   The correct syntax is string.replace(old, new[, count]), where old and new are strings.

2. Step 2: Analyze options

   text.replace('cat', 'dog') matches the correct syntax. Options A, B, and D use invalid syntax or parameters.

3. Final Answer:

   text.replace('cat', 'dog') -> Option B

4. Quick Check:

   replace(old, new) syntax = text.replace('cat', 'dog') [OK]

Hint: Use replace(old, new) without extra keywords [OK]

Common Mistakes:

• Using arrows or keywords inside replace()
• Adding unsupported parameters like all=True
• Confusing parameter order

3. What will be the output of this code?

text = 'apple apple apple'
new_text = text.replace('apple', 'orange', 2)
print(new_text)

medium

A. 'apple orange orange'

B. 'orange orange orange'

C. 'orange orange apple'

D. 'apple apple orange'

Solution

1. Step 1: Understand replace with count

   The third argument 2 limits replacements to first two occurrences.

2. Step 2: Apply replacements

   First two 'apple' become 'orange', last remains 'apple'. Result: 'orange orange apple'.

3. Final Answer:

   'orange orange apple' -> Option C

4. Quick Check:

   replace with count=2 changes first two only [OK]

Hint: Count limits how many replacements happen [OK]

Common Mistakes:

• Replacing all occurrences ignoring count
• Replacing from the end instead of start
• Miscounting number of replacements

4. The following code tries to replace 'blue' with 'red' but causes an error. What is the error?

text = 'blue sky'
text.replace('blue', 'red', 'all')
print(text)

medium

A. SyntaxError due to wrong quotes

B. AttributeError because replace is not a string method

C. No error, prints 'red sky'

D. TypeError because 'all' is not an integer for count

Solution

1. Step 1: Check replace() parameters

   The third parameter must be an integer count, but 'all' is a string.

2. Step 2: Identify error type

   Passing a string instead of int causes a TypeError at runtime.

3. Final Answer:

   TypeError because 'all' is not an integer for count -> Option D

4. Quick Check:

   replace count must be int, not string [OK]

Hint: Count parameter must be integer, not string [OK]

Common Mistakes:

• Using strings instead of integers for count
• Expecting replace to modify original string
• Confusing error types

5. You have a paragraph stored in text. You want to replace only the first 3 occurrences of the word 'error' with 'issue'. Which code snippet correctly does this?

hard

A. new_text = text.replace('error', 'issue', 3)

B. new_text = text.replace('error', 'issue', count=3)

C. new_text = text.replace('error', 'issue', '3')

D. new_text = text.replace('error', 'issue')[:3]

Solution

1. Step 1: Use replace with count parameter

   To replace only first 3 occurrences, use replace(old, new, count) with count=3.

2. Step 2: Analyze options

   new_text = text.replace('error', 'issue', 3) uses correct syntax. new_text = text.replace('error', 'issue', count=3) uses invalid keyword argument. new_text = text.replace('error', 'issue', '3') passes count as string. new_text = text.replace('error', 'issue')[:3] slices string incorrectly.

3. Final Answer:

   new_text = text.replace('error', 'issue', 3) -> Option A

4. Quick Check:

   replace(old, new, 3) replaces first 3 only [OK]

Hint: Use third argument as integer count for limited replacements [OK]

Common Mistakes:

• Using keyword count instead of positional argument
• Passing count as string instead of int
• Trying to slice string after replace