Generate Bigrams Using Python List Comprehension and Zip
Company: PayPal
Role: Data Scientist
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
##### Scenario
Live Python exercise: generate all bigrams from an input string and iteratively optimize the solution.
##### Question
Write a Python function that takes a sentence and returns a list of all consecutive word bigrams. Refactor the solution with list comprehension for conciseness. Can you further compress it into a single line? (Hint: consider using zip.)
##### Hints
Think of zip(s.split()[:-1], s.split()[1:]) and join/format as needed.
Quick Answer: This question evaluates proficiency in Python programming, particularly list comprehension, string tokenization, and sequence manipulation for generating consecutive word bigrams.
Write a function that takes a sentence (string) and returns a list of all consecutive word bigrams. A bigram is a pair of adjacent words joined by a single space, in order. Split the sentence on whitespace (collapsing any runs of whitespace) before pairing.
For example, given "the quick brown fox", return ["the quick", "quick brown", "brown fox"]. A sentence with fewer than two words yields an empty list.
This mirrors the classic zip-based idiom: pairing words[:-1] with words[1:]. Try a loop first, then refactor into a one-line list comprehension over zip(words[:-1], words[1:]).
Constraints
- The input is a single string that may contain leading, trailing, or repeated whitespace.
- Words are maximal non-whitespace runs; splitting collapses any whitespace.
- A sentence with zero or one word returns an empty list.
- Each bigram is the two adjacent words joined by exactly one space.
Examples
Input: ("the quick brown fox",)
Expected Output: ["the quick", "quick brown", "brown fox"]
Explanation: Four words produce three consecutive bigrams.
Input: ("hello world",)
Expected Output: ["hello world"]
Explanation: Two words produce exactly one bigram.
Hints
- Split the sentence into a list of words first using whitespace splitting (which collapses repeated spaces).
- Pair each word with the one that follows it: index i with index i+1, for i from 0 to len(words)-2.
- The one-line idiom is [a + ' ' + b for a, b in zip(words[:-1], words[1:])] — zip naturally stops at the shorter sequence, so it produces exactly len(words)-1 pairs.