Python Essentials for Data Analytics
Back to PANDAS FOR DATA ANALYTICS

Reading & Writing Data

Understand how to import and export CSV, Excel, and JSON files using pandas—your first step into real datasets.

33 minutesVideo LessonPDF notes
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Key moments

  1. CSV Read and Write — The standard methods `read_csv` and `to_csv` are demonstrated, including setting the index column upon import.
  2. Tab-Delimited Files — Tab-delimited files are handled by passing the custom separator `sep='\t'` to the standard CSV methods.
  3. Excel Dependencies — External packages like `openpyxl`, `xlwt`, and `xlrd` must be installed to enable Excel file interaction.
  4. Excel I/O Methods — The dedicated methods `to_excel` and `read_excel` are used to export and import data from XLSX files.
  5. Default JSON Export — The `to_json` method is introduced, which defaults to a dictionary-like orientation where columns are keys.
  6. JSON Orientation Control — Using `orient='records'` and `lines=True` creates a list-like JSON structure that is often easier to read and process.
PDF notes

Frequently asked questions

Why do I need to install extra packages for Excel but not CSV?

CSV is a simple text format that Pandas handles natively, but Excel files are complex binary formats requiring specialized libraries like `openpyxl` to parse and generate.

How do I read a file that uses a semicolon (;) instead of a comma?

Use the `sep` argument in `pd.read_csv()`, setting it to the custom delimiter, e.g., `sep=';'`.

What is the difference between the default JSON orientation and `orient='records'`?

Default (dictionary-like) groups data by column; `orient='records'` groups data by row, making it list-like and often easier for line-by-line processing.

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