NumPy Format

Read and write NumPy .npy / .npz arrays as flat row dictionaries.

Overview

Property	Value
Format id	npy (alias npz)
Class	NumPyIterable
Extensions	.npy, .npz
Read	Yes
Write	Yes
Extra	npy (numpy)
Maturity	stable

Record shape

Array rank	Record
1D	{"value": scalar} per element
2D	{"col_0": ..., "col_1": ..., ...} per row

Only 1D/2D arrays are supported. Requires a filename (not a stream).

Parameters

Parameter	Description
array_name	For .npz, array to iterate (default: first); used on write as the saved name

list_tables() returns array names for .npz (or None for .npy). totals() is the leading axis length. Writes buffer rows and flush on close().

Usage

from iterable import open_iterable

with open_iterable("matrix.npy") as source:
    for row in source:
        print(row)

with open_iterable("data.npz", iterableargs={"array_name": "X"}) as source:
    for row in source:
        print(row)

Install with pip install iterabledata[npy].

See also

• MATLAB MAT — MATLAB variables
• Supported formats