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pynmea2
=======
`pynmea2` is a python library for the [NMEA 0183](http://en.wikipedia.org/wiki/NMEA_0183) protocol
`pynmea2` is based on [`pynmea`](https://code.google.com/p/pynmea/) by Becky Lewis
The `pynmea2` homepage is located at http://github.com/Knio/pynmea2
### Compatibility
`pynmea2` is compatable with Python 2.7 and Python 3.4+
[](https://www.travis-ci.com/Knio/pynmea2)
[](https://coveralls.io/r/Knio/pynmea2?branch=master)
### Installation
The recommended way to install `pynmea2` is with
[pip](http://pypi.python.org/pypi/pip/):
pip install pynmea2
[](https://pypi.org/project/pynmea2/)
[](https://pypi.org/project/pynmea2/)
Parsing
-------
You can parse individual NMEA sentences using the `parse(data, check=False)` function, which takes a string containing a
NMEA 0183 sentence and returns a `NMEASentence` object. Note that the leading '$' is optional and trailing whitespace is ignored when parsing a sentence.
With `check=False`, `parse` will accept NMEA messages that do not have checksums, however it will still raise `pynmea2.ChecksumError` if they are present. `check=True` will also raise `ChecksumError` if the checksum is missing.
Example:
```python
>>> import pynmea2
>>> msg = pynmea2.parse("$GPGGA,184353.07,1929.045,S,02410.506,E,1,04,2.6,100.00,M,-33.9,M,,0000*6D")
>>> msg
<GGA(timestamp=datetime.time(18, 43, 53), lat='1929.045', lat_dir='S', lon='02410.506', lon_dir='E', gps_qual='1', num_sats='04', horizontal_dil='2.6', altitude=100.0, altitude_units='M', geo_sep='-33.9', geo_sep_units='M', age_gps_data='', ref_station_id='0000')>
```
The `NMEASentence` object has different properties, depending on its sentence type.
The `GGA` message has the following properties:
```python
>>> msg.timestamp
datetime.time(18, 43, 53)
>>> msg.lat
'1929.045'
>>> msg.lat_dir
'S'
>>> msg.lon
'02410.506'
>>> msg.lon_dir
'E'
>>> msg.gps_qual
'1'
>>> msg.num_sats
'04'
>>> msg.horizontal_dil
'2.6'
>>> msg.altitude
100.0
>>> msg.altitude_units
'M'
>>> msg.geo_sep
'-33.9'
>>> msg.geo_sep_units
'M'
>>> msg.age_gps_data
''
>>> msg.ref_station_id
'0000'
```
Additional properties besides the ones explicitly in the message data may also exist.
For example, `latitude` and `longitude` properties exist as helpers to access the geographic coordinates as python floats ([DD](http://en.wikipedia.org/wiki/Decimal_degrees), "decimal degrees") instead of the DDDMM.MMMM ("Degrees, minutes, seconds") format used in the NMEA protocol. `latitude_minutes`, `latitude_seconds`, `longitude_minutes`, and `longitude_seconds` are also supported and allow easy creation of differently formatted location strings.
```python
>>> msg.latitude
-19.4840833333
>>> msg.longitude
24.1751
>>> '%02d°%07.4f′' % (msg.latitude, msg.latitude_minutes)
'-19°29.0450′'
>>> '%02d°%02d′%07.4f″' % (msg.latitude, msg.latitude_minutes, msg.latitude_seconds)
"-19°29′02.7000″"
```
Generating
----------
You can create a `NMEASentence` object by calling the constructor with talker, message type, and data fields:
```python
>>> import pynmea2
>>> msg = pynmea2.GGA('GP', 'GGA', ('184353.07', '1929.045', 'S', '02410.506', 'E', '1', '04', '2.6', '100.00', 'M', '-33.9', 'M', '', '0000'))
```
and generate a NMEA string from a `NMEASentence` object:
```python
>>> str(msg)
'$GPGGA,184353.07,1929.045,S,02410.506,E,1,04,2.6,100.00,M,-33.9,M,,0000*6D'
```
File reading example
--------
See [examples/read_file.py](/examples/read_file.py)
```python
import pynmea2
file = open('examples/data.log', encoding='utf-8')
for line in file.readlines():
try:
msg = pynmea2.parse(line)
print(repr(msg))
except pynmea2.ParseError as e:
print('Parse error: {}'.format(e))
continue
```
pySerial device example
---------
See [examples/read_serial.py](/examples/read_serial.py)
```python
import io
import pynmea2
import serial
ser = serial.Serial('/dev/ttyS1', 9600, timeout=5.0)
sio = io.TextIOWrapper(io.BufferedRWPair(ser, ser))
while 1:
try:
line = sio.readline()
msg = pynmea2.parse(line)
print(repr(msg))
except serial.SerialException as e:
print('Device error: {}'.format(e))
break
except pynmea2.ParseError as e:
print('Parse error: {}'.format(e))
continue
```
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