PyAIS

3.0.0 verified Fri May 01 auth: no python

A Python library for decoding and encoding AIS (Automatic Identification System) messages used in maritime navigation. Current version 3.0.0 (released 2024) with ~35% faster performance, requires Python >=3.9. No regular release cadence; version 2.x was stable for years.

pip install pyais

Common errors

error ModuleNotFoundError: No module named 'pyais.decode' ↓

cause Importing decode as a submodule instead of top-level function.

fix

Use 'from pyais import decode'.

error AttributeError: 'AISSentence' object has no attribute 'bit_array' ↓

cause Using deprecated attribute from v2.x. In v3.0.0, 'bit_array' was renamed to 'bv'.

fix

Replace 'bit_array' with 'bv'.

error TypeError: decode() missing 1 required positional argument: 'sentence' ↓

cause Calling decode on a list or forgetting to pass the sentence string.

fix

Ensure you pass a single NMEA sentence string to decode().

Warnings

breaking v3.0.0 renamed AISSentence.bit_array to AISSentence.bv and Payload.from_bitarray() to Payload.from_vector(), Payload.to_bitarray() to Payload.to_bytes(). Code using old names will break. ↓

fix Replace .bit_array with .bv, .from_bitarray() with .from_vector(), .to_bitarray() with .to_bytes().

breaking v3.0.0 removed the bitarray dependency; replaced with custom bit_vector. Imports like 'from bitarray import bitarray' may not work for pyais internals. ↓

fix Do not rely on bitarray for pyais objects; use pyais's built-in bit vector.

deprecated NonPrintableCharacterException has been deprecated in v3.0.0 and may be removed in future. ↓

fix Catch generic Exception or use pyais's custom exceptions; avoid relying on NonPrintableCharacterException.

gotcha decode() can raise pyais.exceptions.DecodingError if the message is malformed or checksum fails. New users may not handle exceptions. ↓

fix Wrap decode() in try/except or validate checksum separately using pyais.checksum.

Imports

decode
wrong
```
from pyais.decode import decode
```
correct
```
from pyais import decode
```
decode is a top-level function, not a submodule. Wrong import raises ModuleNotFoundError.
AISSentence
wrong
```
from pyais.messages import AISSentence
```
correct
```
from pyais import AISSentence
```
AISSentence is exported from pyais; accessing submodule path may break or not exist.
Payload
wrong
```
from pyais.payload import Payload
```
correct
```
from pyais import Payload
```
Payload is a top-level export. Direct submodule import may fail.

Quickstart

Decode a single AIS message from an NMEA 0183 sentence.

from pyais import decode

# NMEA 0183 AIS message string
msg = "!AIVDM,1,1,,A,133m@ogP00PD;88MD5MTDww@2D7k,0*46"
decoded = decode(msg)
print(decoded)
print(decoded.asdict())