Study guide: Read Text Files and Structured Formats
Interpret CSV A,"red,blue",5 and JSON {"id":"007","count":5}. Plan a read-only source inspection and a separate derived output.
Ideas to explain in your own words
- Python strip removes specified leading and trailing characters, or surrounding whitespace when no characters are specified. It does not remove every internal space. Normalization must fit the data contract; removing meaningful content could corrupt a label. Our examples trim only incidental surrounding spaces.
- CSV quoting can keep a separator inside one field. In our stated dialect comma separates fields and a double-quoted phrase can include a comma. Splitting every comma blindly breaks that row. A parser should use the documented dialect; the paper exercise supplies its rules.
- JSON represents objects, arrays and primitive values with defined syntax. An object maps text keys to values. Quoted digits are text rather than a numeric quantity. The supplied data is a small original object; parsing it does not imply its fields satisfy an application’s business rules.
- File operations can read, overwrite or append under their stated mode. A workflow should choose a mode that matches its purpose and protect originals before a transformation. Our paper task describes Python-style modes without opening files. No learner’s actual records are needed.
Useful vocabulary
- CSV quoting
- Rules allowing separators inside a field.
- JSON object
- Text keys associated with structured values.
- file mode
- The requested type of file operation.
Watch your reasoning
- Do not collapse an internal space just because surrounding whitespace is trimmed.
- A comma inside a quoted field is not a new column boundary.
- Valid JSON syntax is different from a valid application record.
- Opening a destination for writing can replace existing content; do not treat it as harmless inspection.
A worked review example
Paper Python 3 expression: " red ".strip(). What value results? The supported answer is 'red'. Tracing the expression under Python 3 rules gives 'red'. Remove surrounding whitespace and preserve characters inside the stated text. Do not collapse an internal space just because surrounding whitespace is trimmed. Python strip removes specified leading and trailing characters, or surrounding whitespace when no characters are specified. Purpose: inspect original without changing it. Which stated plan fits the purpose? The supported answer is Read original. Use read mode for inspection and a separate destination when the original must remain. Opening a destination for writing can replace existing content; do not treat it as harmless inspection. The supplied facts, rather than an assumed real-world detail, determine this paper case. Compare the recorded action or value with the stated rule before choosing an answer.
Make a practice plan
- Make a four-row summary, one row for each lesson, with its computing idea and one worked decision.
- Explain one tempting mistake using the actual supplied example.
- Complete the new unit review before consulting its explanations.
- Try the transfer task on paper and compare your evidence against the model response.