Code Explanation:
๐น 1. Importing compress
from itertools import compress
✅ Explanation
compress() is imported from Python's itertools module.
It is used to filter one iterable using another iterable.
It works like a filter mask.
Think of it like a TV remote.
Letters
A B C D
Selectors
1 0 1 0
1 = Keep ✅
0 = Remove ❌
๐น 2. Creating the Data List
letters = ["A", "B", "C", "D"]
✅ Explanation
A list named letters is created.
Current memory:
letters
│
▼
["A","B","C","D"]
These are the values that may be selected.
๐น 3. Creating the Selector List
selectors = [1, 0, 1, 0]
✅ Explanation
Another list named selectors is created.
Current memory:
selectors
│
▼
[1,0,1,0]
Each selector corresponds to one letter.
Relationship:
Letter A B C D
Selector 1 0 1 0
๐น 4. Calling compress()
compress(letters, selectors)
✅ Explanation
Syntax:
compress(data, selectors)
Python compares both lists position by position.
Rule:
Selector = 1
↓
Keep the value
Selector = 0
↓
Discard the value
๐น 5. First Comparison
Current values:
Letter = A
Selector = 1
Condition:
1 → True
Action:
Keep A ✅
Current result:
[A]
๐น 6. Second Comparison
Current values:
Letter = B
Selector = 0
Condition:
0 → False
Action:
Remove B ❌
Current result:
[A]
๐น 7. Third Comparison
Current values:
Letter = C
Selector = 1
Condition:
1 → True
Action:
Keep C ✅
Current result:
[A, C]
๐น 8. Fourth Comparison
Current values:
Letter = D
Selector = 0
Condition:
0 → False
Action:
Discard D ❌
Final result becomes:
[A, C]
๐น 9. Converting to a List
list(compress(...))
✅ Explanation
compress() returns an iterator.
list() converts it into a normal Python list.
Current value:
["A", "C"]
๐น 10. Printing the Result
print(list(compress(letters, selectors)))
✅ Explanation
Python prints the final filtered list.
Output:
['A', 'C']
๐ฏ Final Output
['A', 'C']
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