Describe the Use of Lists, Dictionaries, Tuples, Sets, and Strings DATA-ENGINEERING-OPTIMIZE Practice Questions (Page 5)

Questions 21–24

1. 21foundation · easy

   What does `numbers[1:4]` return if `numbers = [10, 20, 30, 40, 50]`?

   • A[10, 20, 30]
   • B[20, 30, 40]
   • C[30, 40]
   • D[20, 30, 40, 50]
   Reveal Solution Discussion Select an answer first
2. 22expert · hard

   A data engineer has two lists of IP addresses: `allowed_ips` and `blocked_ips`. The engineer needs to create a list of IPs that are in `allowed_ips` but NOT in `blocked_ips`, preserving the original order from `allowed_ips`. Which approach is the most efficient?

   • AUse a nested loop: [ip for ip in allowed_ips if ip not in blocked_ips]
   • BConvert `allowed_ips` to a set and use set difference, then convert back to a list
   • CConvert `blocked_ips` to a set and use a list comprehension: [ip for ip in allowed_ips if ip not in blocked_set]
   • DConvert both lists to sets and use set difference, then convert back to a list
   Reveal Solution Discussion Select an answer first
4. 23application · medium

   A pipeline processes sensor readings where each reading has a sensor ID and a timestamp. The engineer needs to store the timestamp for each sensor so that the latest reading can be retrieved quickly by sensor ID. The data will be updated frequently as new readings arrive. Which data structure should be used?

   • AA list of tuples, where each tuple is (sensor_id, timestamp)
   • BA tuple of (sensor_id, timestamp) pairs
   • CA set of timestamps only
   • DA dictionary mapping sensor_id to timestamp
   Reveal Solution Discussion Select an answer first
5. 24application · easy

   A data engineer has a list of 1000 timestamps and needs to create a new list containing only the timestamps at even indices (0, 2, 4, ...). Which Python expression accomplishes this?

   • Atimestamps[1::2]
   • Btimestamps[::3]
   • Ctimestamps[::2]
   • Dtimestamps[0:len(timestamps):2]
   Reveal Solution Discussion Select an answer first