awips2/cave/com.raytheon.uf.viz.derivparam.python/localization/derivedParameters/functions/Vector.py

##
# This software was developed and / or modified by Raytheon Company,
# pursuant to Contract DG133W-05-CQ-1067 with the US Government.
# 
# U.S. EXPORT CONTROLLED TECHNICAL DATA
# This software product contains export-restricted data whose
# export/transfer/disclosure is restricted by U.S. law. Dissemination
# to non-U.S. persons whether in the United States or abroad requires
# an export license or other authorization.
# 
# Contractor Name:        Raytheon Company
# Contractor Address:     6825 Pine Street, Suite 340
#                         Mail Stop B8
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#                         402.291.0100
# 
# See the AWIPS II Master Rights File ("Master Rights File.pdf") for
# further licensing information.
##

from numpy import arctan2
from numpy import hypot
from numpy import cos
from numpy import sin
from numpy import degrees
from numpy import radians
from numpy import abs
from numpy import isscalar, empty, float32

def execute(u, v, magDir=None):
    """ Make a vector from u,v or mag, dir.
      
      @param magDir
                 controls how the function operates on the given u and v values.
                 When the magDir is specified and is a constant scalar value
                 the u and v input values are assumed to be speed and direction.

                 positive :: assume meteorological direction(direction from)
                 negative :: assume mathematical direction(direction to)
      
                 abs(legacyOption) == 1 :: assume direction in degrees
                 abs(legacyOption) != 1 :: assume direction in radians

      @return: tuple of (u,v)
    
    """
    # If either u or v is a single number, expand it to match an entire Grid
    if isscalar(u) and not(isscalar(v)):
        tmp = empty(v.shape, float32)
        tmp.fill(u)
        u = tmp
        
    if isscalar(v) and not(isscalar(u)):
        tmp = empty(u.shape, float32)
        tmp.fill(v)
        v = tmp
    
    if magDir == None:
        return componentsTo(u, v)
    elif magDir == 1:
        return magDirDegreesFrom(u, v);
    elif magDir == -1:
        return magDirDegreesTo(u, v);
    elif magDir >= 0:
        return magDirRadiansFrom(u, v);
    else:
        return magDirRadiansTo(u, v);

def componentsTo(u,v):
    return (u, v)

def magDirRadiansTo(mag, dir):
    u = sin(dir) * mag
    v = cos(dir) * mag
    return componentsTo(u,v)

def magDirDegreesTo(mag, dir):
    return magDirRadiansTo(mag, radians(dir))

def componentsFrom(u,v):
    return componentsTo(-u,-v)

def magDirRadiansFrom(mag, dir):
    u = sin(dir) * mag
    v = cos(dir) * mag
    return componentFrom(u,v)

def magDirDegreesFrom(mag, dir):
    return magDirRadiansFrom(mag, radians(dir))