Chapter 5

Lists and Ordered Values

Select, build, pair, summarize, transform, and order familiar values while keeping the ordinary loop behind each compact Python form visible.

Chapter 4 treated `readings` as one input. Here we will inspect one position or range, collect a new result list, and transform one short text label without losing sight of the source values.

Positions become more useful when they remain aligned with labels and readings. Small tuples, `enumerate`, and `zip` will make those relationships visible. Familiar accumulator loops will then lead to `sum`, `min`, `max`, `any`, and `all` only after their meaning and empty-input boundaries are clear.

The final lessons derive a list comprehension from its ordinary loop, use the same form directly inside a known summary, and order labelled results through a named comparison key. Every compact form can be expanded into work that the reader already knows how to trace.

After this chapter

  • Select one item or an ordinary range from a list, tuple, or string and guard an empty sequence before indexing.
  • Build a result list with append while distinguishing mutation from the method's None return value.
  • Trace strip, lower, split, and join through one short text transformation without changing the source string.
  • Unpack fixed pairs and align positions, labels, and readings with enumerate and checked zip calls.
  • Relate sum, min, max, any, and all to familiar loops and state their relevant empty-input behavior.
  • Expand list comprehensions and generator expressions into visible loops, choosing a named result list when inspection matters.
  • Order labelled results with sorted and a named key while preserving the source sequence.

Lessons

  1. 01
    Select from Lists and Text

    Select items and ranges from lists, tuples, and text; test membership; and guard empty sequences.

    3 exercises
  2. 02
    Build and Change Lists

    Build result lists with append, trace visible mutation, and keep method return values separate from changed lists.

    3 exercises
  3. 03
    Split and Join Text

    Transform a short text value with strip, lower, split, and join without changing its source string.

    3 exercises
  4. 04
    Pair and Unpack Values

    Unpack fixed pairs, pair values with positions, zip aligned sequences, and reject unequal lengths when truncation would be wrong.

    3 exercises
  5. 05
    Summarize Existing Sequences

    Summarize existing numerical and Boolean sequences with checked standard operations and explicit empty boundaries.

    3 exercises
  6. 06
    Transform Values with a Comprehension

    Build transformed lists with readable comprehensions and expand compact forms back into ordinary loops.

    3 exercises
  7. 07
    Summarize Transformed Values

    Read generator expressions inside known summaries and expand them into visible lists or loops when inspection matters.

    3 exercises
  8. 08
    Order Values Predictably

    Use sorted, reverse order, named key functions, tuple tie-breaking, and one equivalent simple lambda.

    3 exercises

Review and practice

  1. •
    Review

    Review selection, mutation, text parts, paired values, summaries, comprehensions, generators, and sorting.

  2. •
    Exercises

    Practice selection, list construction, text transformation, pairing, summaries, comprehensions, generators, and named sorting keys.

Chapter progress