Source code for astrocalc.coords.translate

#!/usr/local/bin/python
# encoding: utf-8
"""
*Calculations to translate coordinates across the sky*

Author
: David Young
"""
from __future__ import division
from builtins import object
from past.utils import old_div
import sys
import os
import math
os.environ['TERM'] = 'vt100'




class translate(object):
    """
    *Translate a set of coordinates north and east by distances given in arcsecs*

    **Key Arguments**

    - ``log`` -- logger
    - ``settings`` -- the settings dictionary. Default *False*
    - ``ra`` -- ra (decimal or sexegesimal)
    - ``dec`` -- dec (decimal or sexegesimal)
    - ``northArcsec`` -- number of arcsecs to move location to the north
    - ``eastArcsec`` -- number of arcsecs to move location to the east


    .. todo::

        - replace shift_coordinates class in all other code

    **Usage**

    To shift a set of coordinates north and east by given distances:

    ```python
    # TRANSLATE COORDINATES ACROSS SKY
    from astrocalc.coords import translate
    ra, dec = translate(
        log=log,
        settings=settings,
        ra="14.546438",
        dec="-45.34232334",
        northArcsec=4560,
        eastArcsec=+967800
    ).get()  
    ```

    """
    # Initialisation

    def __init__(
            self,
            log,
            ra,
            dec,
            northArcsec,
            eastArcsec,
            settings=False,
    ):
        self.log = log
        log.debug("instansiating a new 'translate' object")
        self.settings = settings
        self.ra = ra
        self.dec = dec
        self.north = northArcsec / 3600.
        self.east = eastArcsec / 3600.
        # xt-self-arg-tmpx

        # CONSTANTS
        self.pi = (4 * math.atan(1.0))
        self.DEG_TO_RAD_FACTOR = self.pi / 180.0
        self.RAD_TO_DEG_FACTOR = 180.0 / self.pi

        # INITIAL ACTIONS
        # CONVERT RA AND DEC INTO DECIMAL DEGREES
        from astrocalc.coords import unit_conversion
        converter = unit_conversion(
            log=log
        )
        self.ra = converter.ra_sexegesimal_to_decimal(
            ra=self.ra
        )
        self.dec = converter.dec_sexegesimal_to_decimal(
            dec=self.dec
        )

        return None



    def get(self):
        """
        *translate the coordinates*

        **Return**

        - ``ra`` -- the right-ascension of the translated coordinate
        - ``dec`` -- the declination of the translated coordinate

        """
        self.log.debug('starting the ``get`` method')

        # PRECISION TEST
        decprecision = len(repr(self.dec).split(".")[-1])
        raprecision = len(repr(self.ra).split(".")[-1])

        dec2 = self.dec + self.north

        ra2 = self.ra + \
            (old_div((self.east),
                     (math.cos((self.dec + dec2) * self.DEG_TO_RAD_FACTOR / 2.))))

        # FIX VALUES THAT CROSS RA/DEC LIMITS
        while ra2 > 360. or ra2 < 0.:
            while ra2 > 360.:
                ra2 = ra2 - 360.
            while ra2 < 0.:
                ra2 = ra2 + 360.
        while dec2 > 90. or dec2 < -90.:
            while dec2 > 90.:
                dec2 = 180. - dec2
            while dec2 < -90.:
                dec2 = -180. - dec2

        ra2 = "%0.*f" % (raprecision, ra2)
        dec2 = "%0.*f" % (decprecision, dec2)

        self.log.debug('completed the ``get`` method')
        return ra2, dec2



    # xt-class-method