Add vectorized version of df and typecode functions.

pyModeS/__init__.py

@@ -1,13 +1,7 @@
 import os
 import warnings
 
-try:
+from .common import *
-    from . import c_common as common
-    from .c_common import *
-except:
-    from . import py_common as common
-    from .py_common import *
-
 from .decoder import tell
 from .decoder import adsb
 from .decoder import commb

pyModeS/common.py

@@ -0,0 +1,48 @@
+import typing as tp
+from functools import singledispatch
+
+from .vec import common as common_vec
+from .vec.types import InputData
+try:
+    from . import c_common as common_str
+except:
+    from . import py_common as common_str
+
+@singledispatch
+def df(msg: tp.Any) -> int:
+    raise NotImplementedError('Only string and NumPy arrays supported')
+
+@df.register
+def _df_str(msg: str) -> int:
+    return common_str.df(msg)
+
+@df.register
+def _df_vec(msg: InputData) -> int:
+    return common_vec.df(msg)
+
+@singledispatch
+def typecode(msg: tp.Any) -> int:
+    raise NotImplementedError('Only string and NumPy arrays supported')
+
+@typecode.register
+def _tc_str(msg: str) -> int:
+    return common_str.typecode(msg)
+
+@typecode.register
+def _tc_vec(msg: InputData) -> int:
+    return common_vec.typecode(msg)
+
+icao = common_str.icao
+altitude = common_str.altitude
+altcode = common_str.altcode
+allzeros = common_str.allzeros
+data = common_str.data
+wrongstatus = common_str.wrongstatus
+idcode = common_str.idcode
+floor = common_str.floor
+cprNL = common_str.cprNL
+crc = common_str.crc
+squawk = common_str.squawk
+hex2bin = common_str.hex2bin
+hex2bin = common_str.hex2bin
+bin2int = common_str.bin2int

pyModeS/vec/common.py

@@ -0,0 +1,34 @@
+import numpy as np
+import typing as tp
+
+from .util import create_array
+from .types import InputData, DownlinkFormat, TypeCode
+
+
+def df(data: InputData) -> DownlinkFormat:
+    """
+    Parse downlink format address from ADS-B messages.
+
+    :param data: ADS-B messages.
+
+    ..seealso:: `Message structure <https://mode-s.org/decode/content/ads-b/1-basics.html>`_
+    """
+    result = (data[:, 0] & 0xf8) >> 3
+    result[result > 24] = 24
+    return result
+
+def typecode(data: InputData, df_data: tp.Optional[DownlinkFormat]=None) -> TypeCode:
+    """
+    Parse type code information from ADS-B messages.
+
+    :param data: ADS-B messages.
+    :param df_data: Optional downlink format information for each ADS-B
+        message.
+
+    ..seealso:: `ADS-B message types <https://mode-s.org/decode/content/ads-b/1-basics.html>`_
+    """
+    result = np.zeros(len(data), dtype=np.uint8)
+    df_v = df(data) if df_data is None else df_data
+    idx = (df_v == 17) | (df_v == 18)
+    result[idx] = data[idx, 4] >> 3
+    return create_array(result, idx)

pyModeS/vec/ctor.py

@@ -0,0 +1,15 @@
+import numpy as np
+import typing as tp
+
+from .types import InputData
+
+def array(data: tp.Sequence[bytes]) -> InputData:
+    """
+    Create Numpy array, which is input for parsing functions.
+
+    :param data: Collection of ADS-B messages.
+    """
+    vec = np.array(data)
+    result = vec.view(dtype=np.uint8)
+    return result.reshape(-1, 14)
+

pyModeS/vec/types.py

@@ -0,0 +1,9 @@
+import numpy as np
+
+# define aliases for basic types to support static type analysis; these for
+# convenience
+# NOTE: more specific types can be defined when numpy 1.20 is released,
+# i.e. use of np.ndarray[dtype, shape] shall be possible
+InputData = np.ndarray
+DownlinkFormat = np.ndarray
+TypeCode = np.ndarray

pyModeS/vec/util.py

@@ -0,0 +1,16 @@
+import numpy as np
+
+def create_array(data, idx):
+    """
+    Create NumPy masked array.
+
+    Note, that this function differes from NumPy constructor semantics. The
+    index indicates the valid values (not the invalid as in the default
+    masked array in NumPy).
+
+    :param data: Input data.
+    :param idx: Index of valid values.
+    """
+    return np.ma.array(data, mask=~idx)
+
+# vim: sw=4:et:ai

tests/vec/data.py

@@ -0,0 +1,26 @@
+import numpy as np
+from binascii import unhexlify
+
+from pyModeS.vec.ctor import array
+from pyModeS.vec.common import df
+
+import pytest
+
+@pytest.fixture
+def message():
+    data = [
+        '904ca3a33219741c85465ae1b4c3',  # df = 18
+        'a8281d3030000000000000850d4a',  # df = 21
+        '8d406b902015a678d4d220000000',  # example from https://mode-s.org/decode/content/ads-b/8-error-control.html
+        '904ca3da121010603d04f5df3ecf',  # df = 18, tc = 2
+        '977ba7ca0daa3e1915d83237c86e',  # df = 18, tc = 1
+        '8d4ca2d4234994b5452820e5b7ab',  # df = 17, tc = 4
+    ]
+    return array(np.array([unhexlify(v) for v in data]))
+
+@pytest.fixture
+def df_message(message):
+    return df(message)
+
+# vim: sw=4:et:ai
+

tests/vec/test_common.py

@@ -0,0 +1,20 @@
+import numpy as np
+
+from pyModeS.common import df, typecode
+
+from .data import message
+
+def test_df(message):
+    """
+    Test parsing of ADS-B downlink format.
+    """
+    result = df(message)
+    assert np.array_equal([18, 21, 17, 18, 18, 17], result)
+
+def test_typecode(message):
+    """
+    Test ADS-B type code parsing.
+    """
+    result = typecode(message)
+    assert np.array_equal([6, 0, 4, 2, 1, 4], result)
+    assert np.array_equal([6, 4, 2, 1, 4], result.compressed())