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This is a Medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at PayPal.

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This question is commonly asked for Data Scientist candidates at PayPal during technical interviews.

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.

Input: ("single",)

Expected Output: []

Explanation: A single word has no adjacent pair, so the result is empty.

Input: ("",)

Expected Output: []

Explanation: An empty string splits into zero words, yielding an empty list.

Input: (" spaced out words ",)

Expected Output: ["spaced out", "out words"]

Explanation: Leading/trailing and repeated whitespace are collapsed by split, leaving three words and two bigrams.

Input: ("a b c d e",)

Expected Output: ["a b", "b c", "c d", "d e"]

Explanation: Five words produce four consecutive bigrams.

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.

Quick Overview

This question evaluates proficiency in Python programming, particularly list comprehension, string tokenization, and sequence manipulation for generating consecutive word bigrams.