University of Arizona, Department of Computer Science

CSc 120: n-grams

Expected Behavior

Write a function ngram(arglist, startpos, length) that returns the n-gram from arglist of length length starting at position startpos, if one exists; and [] otherwise. (The very first element of the list is at position 0. Negative positions refer to counting backwards from the end of the list.)

Examples

  1. Call: ngram([11,22,33,44,55], 0, 3)
    Return value: [11,22,33]

  2. Call: ngram([11,22,33,44,55], 2, 3)
    Return value: [33,44,55]

  3. Call: ngram([11,22,33,44,55], 3, 3)
    Return value: []

  4. Call: ngram([11,22,33,44,55], -4, 3)
    Return value: [22,33,44]

  5. Call: ngram([11,22,33,44,55], 1, 1)
    Return value: [22]