Application: gvSIG desktop » gvSIG scripting

# encoding: utf-8

"""

:class:`.Point` data structure.

"""

import re

from itertools import islice

from geopy import util, units

from geopy.format import (

    DEGREE,

    PRIME,

    DOUBLE_PRIME,

    format_degrees,

    format_distance,

)

from geopy.compat import string_compare

POINT_PATTERN = re.compile(r"""

    .*?

    (?P<latitude>

      (?P<latitude_direction_front>[NS])?[ ]*

        (?P<latitude_degrees>-?%(FLOAT)s)(?:[%(DEGREE)sD\*\u00B0\s][ ]*

        (?:(?P<latitude_arcminutes>%(FLOAT)s)[%(PRIME)s'm][ ]*)?

        (?:(?P<latitude_arcseconds>%(FLOAT)s)[%(DOUBLE_PRIME)s"s][ ]*)?

        )?(?P<latitude_direction_back>[NS])?)

    %(SEP)s

    (?P<longitude>

      (?P<longitude_direction_front>[EW])?[ ]*

      (?P<longitude_degrees>-?%(FLOAT)s)(?:[%(DEGREE)sD\*\u00B0\s][ ]*

      (?:(?P<longitude_arcminutes>%(FLOAT)s)[%(PRIME)s'm][ ]*)?

      (?:(?P<longitude_arcseconds>%(FLOAT)s)[%(DOUBLE_PRIME)s"s][ ]*)?

      )?(?P<longitude_direction_back>[EW])?)(?:

    %(SEP)s

      (?P<altitude>

        (?P<altitude_distance>-?%(FLOAT)s)[ ]*

        (?P<altitude_units>km|m|mi|ft|nm|nmi)))?

    .*?$

""" % {

    "FLOAT": r'\d+(?:\.\d+)?',

    "DEGREE": DEGREE,

    "PRIME": PRIME,

    "DOUBLE_PRIME": DOUBLE_PRIME,

    "SEP": r'\s*[,;/\s]\s*',

}, re.X)

class Point(object):

    """

    A geodetic point with latitude, longitude, and altitude.

    Latitude and longitude are floating point values in degrees.

    Altitude is a floating point value in kilometers. The reference level

    is never considered and is thus application dependent, so be consistent!

    The default for all values is 0.

    Points can be created in a number of ways...

    With longitude, latitude, and altitude::

        >>> p1 = Point(41.5, -81, 0)

        >>> p2 = Point(latitude=41.5, longitude=-81)

    With a sequence of 0 to 3 values (longitude, latitude, altitude)::

        >>> p1 = Point([41.5, -81, 0])

        >>> p2 = Point((41.5, -81))

    Copy another `Point` instance::

        >>> p2 = Point(p1)

        >>> p2 == p1

        True

        >>> p2 is p1

        False

    Give a string containing at least latitude and longitude::

        >>> p1 = Point('41.5,-81.0')

        >>> p2 = Point('41.5 N -81.0 W')

        >>> p3 = Point('-41.5 S, 81.0 E, 2.5km')

        >>> p4 = Point('23 26m 22s N 23 27m 30s E 21.0mi')

        >>> p5 = Point('''3 26' 22" N 23 27' 30" E''')

    Point values can be accessed by name or by index::

        >>> p = Point(41.5, -81.0, 0)

        >>> p.latitude == p[0]

        True

        >>> p.longitude == p[1]

        True

        >>> p.altitude == p[2]

        True

    When unpacking (or iterating), a (latitude, longitude, altitude) tuple is

    returned::

        >>> latitude, longitude, altitude = p

    """

    __slots__ = ("latitude", "longitude", "altitude", "_items")

    POINT_PATTERN = POINT_PATTERN

    def __new__(cls, latitude=None, longitude=None, altitude=None):

        """

        :param float latitude: Latitude of point.

        :param float longitude: Longitude of point.

        :param float altitude: Altitude of point.

        """

        single_arg = longitude is None and altitude is None

        if single_arg and not isinstance(latitude, util.NUMBER_TYPES):

            arg = latitude

            if arg is None: # pragma: no cover

                pass

            elif isinstance(arg, Point):

                return cls.from_point(arg)

            elif isinstance(arg, string_compare):

                return cls.from_string(arg)

            else:

                try:

                    seq = iter(arg)

                except TypeError: # pragma: no cover

                    raise TypeError(

                        "Failed to create Point instance from %r." % (arg,)

                    )

                else:

                    return cls.from_sequence(seq)

        latitude = float(latitude or 0.0)

        if abs(latitude) > 90:

            latitude = ((latitude + 90) % 180) - 90

        longitude = float(longitude or 0.0)

        if abs(longitude) > 180:

            longitude = ((longitude + 180) % 360) - 180

        altitude = float(altitude or 0.0)

        self = super(Point, cls).__new__(cls)

        self.latitude = latitude

        self.longitude = longitude

        self.altitude = altitude

        self._items = [self.latitude, self.longitude, self.altitude]

        return self

    def __getitem__(self, index):

        return self._items[index]

    def __setitem__(self, index, value):

        self._items[index] = value

    def __iter__(self):

        return iter((self.latitude, self.longitude, self.altitude))

    def __repr__(self):

        return "Point(%r, %r, %r)" % tuple(self._items)

    def format(self, altitude=None, deg_char='', min_char='m', sec_char='s'):

        """

        Format decimal degrees (DD) to degrees minutes seconds (DMS)

        """

        latitude = "%s %s" % (

            format_degrees(abs(self.latitude), symbols={

                'deg': deg_char, 'arcmin': min_char, 'arcsec': sec_char

            }),

            self.latitude >= 0 and 'N' or 'S'

        )

        longitude = "%s %s" % (

            format_degrees(abs(self.longitude), symbols={

                'deg': deg_char, 'arcmin': min_char, 'arcsec': sec_char

            }),

            self.longitude >= 0 and 'E' or 'W'

        )

        coordinates = [latitude, longitude]

        if altitude is None:

            altitude = bool(self.altitude)

        if altitude:

            if not isinstance(altitude, string_compare):

                altitude = 'km'

            coordinates.append(self.format_altitude(altitude))

        return ", ".join(coordinates)

    def format_decimal(self, altitude=None):

        """

        Format decimal degrees with altitude

        """

        coordinates = [str(self.latitude), str(self.longitude)]

        if altitude is None:

            altitude = bool(self.altitude)

        if altitude is True:

            if not isinstance(altitude, string_compare):

                altitude = 'km'

            coordinates.append(self.format_altitude(altitude))

        return ", ".join(coordinates)

    def format_altitude(self, unit='km'):

        """

        Foamt altitude with unit

        """

        return format_distance(self.altitude, unit=unit)

    def __str__(self):

        return self.format()

    def __unicode__(self):

        return self.format(

            None, DEGREE, PRIME, DOUBLE_PRIME

        )

    def __eq__(self, other):

        return tuple(self) == tuple(other)

    def __ne__(self, other):

        return tuple(self) != tuple(other)

    @classmethod

    def parse_degrees(cls, degrees, arcminutes, arcseconds, direction=None):

        """

        Parse degrees minutes seconds including direction (N, S, E, W)

        """

        degrees = float(degrees)

        negative = degrees < 0

        arcminutes = float(arcminutes)

        arcseconds = float(arcseconds)

        if arcminutes or arcseconds:

            more = units.degrees(arcminutes=arcminutes, arcseconds=arcseconds)

            if negative:

                degrees -= more

            else:

                degrees += more

        if direction in [None, 'N', 'E']:

            return degrees

        elif direction in ['S', 'W']:

            return -degrees

        else:

            raise ValueError("Invalid direction! Should be one of [NSEW].")

    @classmethod

    def parse_altitude(cls, distance, unit):

        """

        Parse altitude managing units conversion

        """

        if distance is not None:

            distance = float(distance)

            CONVERTERS = {

                'km': lambda d: d,

                'm': lambda d: units.kilometers(meters=d),

                'mi': lambda d: units.kilometers(miles=d),

                'ft': lambda d: units.kilometers(feet=d),

                'nm': lambda d: units.kilometers(nautical=d),

                'nmi': lambda d: units.kilometers(nautical=d)

            }

            try:

                return CONVERTERS[unit](distance)

            except KeyError: # pragma: no cover

                raise NotImplementedError(

                    'Bad distance unit specified, valid are: %r' %

                    CONVERTERS.keys()

                )

        else:

            return distance

    @classmethod

    def from_string(cls, string):

        """

        Create and return a ``Point`` instance from a string containing

        latitude and longitude, and optionally, altitude.

        Latitude and longitude must be in degrees and may be in decimal form

        or indicate arcminutes and arcseconds (labeled with Unicode prime and

        double prime, ASCII quote and double quote or 'm' and 's'). The degree

        symbol is optional and may be included after the decimal places (in

        decimal form) and before the arcminutes and arcseconds otherwise.

        Coordinates given from south and west (indicated by S and W suffixes)

        will be converted to north and east by switching their signs. If no

        (or partial) cardinal directions are given, north and east are the

        assumed directions. Latitude and longitude must be separated by at

        least whitespace, a comma, or a semicolon (each with optional

        surrounding whitespace).

        Altitude, if supplied, must be a decimal number with given units.

        The following unit abbrevations (case-insensitive) are supported:

            - ``km`` (kilometers)

            - ``m`` (meters)

            - ``mi`` (miles)

            - ``ft`` (feet)

            - ``nm``, ``nmi`` (nautical miles)

        Some example strings the will work include:

            - 41.5;-81.0

            - 41.5,-81.0

            - 41.5 -81.0

            - 41.5 N -81.0 W

            - -41.5 S;81.0 E

            - 23 26m 22s N 23 27m 30s E

            - 23 26' 22" N 23 27' 30" E

            - UT: N 39°20' 0'' / W 74°35' 0''

        """

        match = re.match(cls.POINT_PATTERN, re.sub(r"''", r'"', string))

        if match:

            latitude_direction = None

            if match.group("latitude_direction_front"):

                latitude_direction = match.group("latitude_direction_front")

            elif match.group("latitude_direction_back"):

                latitude_direction = match.group("latitude_direction_back")

            longitude_direction = None

            if match.group("longitude_direction_front"):

                longitude_direction = match.group("longitude_direction_front")

            elif match.group("longitude_direction_back"):

                longitude_direction = match.group("longitude_direction_back")

            latitude = cls.parse_degrees(

                match.group('latitude_degrees') or 0.0,

                match.group('latitude_arcminutes') or 0.0,

                match.group('latitude_arcseconds') or 0.0,

                latitude_direction

            )

            longitude = cls.parse_degrees(

                match.group('longitude_degrees') or 0.0,

                match.group('longitude_arcminutes') or 0.0,

                match.group('longitude_arcseconds') or 0.0,

                longitude_direction

            )

            altitude = cls.parse_altitude(

                match.group('altitude_distance'),

                match.group('altitude_units')

            )

            return cls(latitude, longitude, altitude)

        else:

            raise ValueError(

                "Failed to create Point instance from string: unknown format."

            )

    @classmethod

    def from_sequence(cls, seq):

        """

        Create and return a new ``Point`` instance from any iterable with 0 to

        3 elements.  The elements, if present, must be latitude, longitude,

        and altitude, respectively.

        """

        args = tuple(islice(seq, 4))

        return cls(*args)

    @classmethod

    def from_point(cls, point):

        """

        Create and return a new ``Point`` instance from another ``Point``

        instance.

        """

        return cls(point.latitude, point.longitude, point.altitude)