LIBSVM Format

Read and write LIBSVM sparse feature lines (label index:value …).

Overview

Property	Value
Format id	libsvm
Class	LIBSVMIterable
Extensions	.libsvm
Read	Yes
Write	Yes
Extra	none (stdlib)
Maturity	stable

Record shape

{"label": 1, "features": {1: 0.5, 3: 0.8, 5: 1.0}}

Parameters

Parameter	Default	Description
label_key	label	Dict key for the label
features_key	features	Dict key for the sparse feature map

On write, features may be a dict (index→value) or a dense list/tuple (1-based; zeros omitted).

Usage

from iterable import open_iterable

with open_iterable("train.libsvm") as source:
    for row in source:
        print(row["label"], row["features"])

with open_iterable("out.libsvm", mode="w") as dest:
    dest.write({"label": 1, "features": {1: 0.5, 3: 0.8}})

See also

• ARFF — Weka attribute tables
• Supported formats