CDF Format

Read NASA Common Data Format (CDF) files as one dict per record index across variables. CDF is read-only in this release.

Overview

Property	Value
Format id	cdf
Class	CDFIterable
Extensions	.cdf
Read	Yes
Write	No
Extra	cdf (spacepy / NASA CDF C library)
Maturity	stable

File Extensions

• .cdf — NASA Common Data Format

Implementation Details

Reading

• Opens a local filename (or a file object with a name attribute); bare streams without a path are not supported
• Iterates by record index across CDF variables
• Keys are variable names; values are Python scalars or lists (NumPy/CDF types are converted)
• list_tables() returns variable names

Writing

Writing is not supported. Opening with mode="w" raises WriteNotSupportedError.

Key Features

• Record-oriented: one dict per CDF record index
• Variable discovery: list_tables() lists variable names
• Native types: scalars and arrays converted to Python types

Usage

from iterable import open_iterable

with open_iterable("data.cdf", format="cdf") as source:
    print(source.list_tables())
    for row in source:
        print(row)

Record shape:

{"Epoch": "...", "VariableA": 1.2, "VariableB": [0.0, 1.0]}

Parameters

CDF has no format-specific iterableargs. Pass a filename (or a named file object).

Parameter	Type	Default	Required	Description
(none)	—	—	—	No format-specific parameters

Error Handling

• ImportError: Missing spacepy or CDF C library — install with pip install iterabledata[cdf] and see https://cdf.gsfc.nasa.gov for the NASA CDF C library
• WriteNotSupportedError: Raised for mode="w" (CDF is read-only)
• ReadError: Cannot open the file, or no filename / named file object is available
• FileNotFoundError: Path is wrong or the file is missing

See Troubleshooting for more help.

Installation

pip install 'iterabledata[cdf]'

Also requires the NASA CDF C library (https://cdf.gsfc.nasa.gov).

Limitations

1. Read-only
2. Filename (or named file object) required
3. Requires spacepy and the NASA CDF C library

Related Formats

• NetCDF — NetCDF scientific arrays
• HDF5 — hierarchical arrays