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#===========================================================================
#
# UnitDbl
#
#===========================================================================
"""UnitDbl module."""
#===========================================================================
# Place all imports after here.
#
#
# Place all imports before here.
#===========================================================================
#===========================================================================
class UnitDbl:
"""Class UnitDbl in development.
"""
#-----------------------------------------------------------------------
# Unit conversion table. Small subset of the full one but enough
# to test the required functions. First field is a scale factor to
# convert the input units to the units of the second field. Only
# units in this table are allowed.
allowed = {
"m" : ( 0.001, "km" ),
"km" : ( 1, "km" ),
"mile" : ( 1.609344, "km" ),
"rad" : ( 1, "rad" ),
"deg" : ( 1.745329251994330e-02, "rad" ),
"sec" : ( 1, "sec" ),
"min" : ( 60.0, "sec" ),
"hour" : ( 3600, "sec" ),
}
_types = {
"km" : "distance",
"rad" : "angle",
"sec" : "time",
}
#-----------------------------------------------------------------------
def __init__( self, value, units ):
"""Create a new UnitDbl object.
Units are internally converted to km, rad, and sec. The only
valid inputs for units are [ m, km, mile, rad, deg, sec, min, hour ].
The field UnitDbl.value will contain the converted value. Use
the convert() method to get a specific type of units back.
= ERROR CONDITIONS
- If the input units are not in the allowed list, an error is thrown.
= INPUT VARIABLES
- value The numeric value of the UnitDbl.
- units The string name of the units the value is in.
"""
self.checkUnits( units )
data = self.allowed[ units ]
self._value = float( value * data[0] )
self._units = data[1]
#-----------------------------------------------------------------------
def convert( self, units ):
"""Convert the UnitDbl to a specific set of units.
= ERROR CONDITIONS
- If the input units are not in the allowed list, an error is thrown.
= INPUT VARIABLES
- units The string name of the units to convert to.
= RETURN VALUE
- Returns the value of the UnitDbl in the requested units as a floating
point number.
"""
if self._units == units:
return self._value
self.checkUnits( units )
data = self.allowed[ units ]
if self._units != data[1]:
msg = "Error trying to convert to different units.\n" \
" Invalid conversion requested.\n" \
" UnitDbl: %s\n" \
" Units: %s\n" % ( str( self ), units )
raise ValueError( msg )
return self._value / data[0]
#-----------------------------------------------------------------------
def __abs__( self ):
"""Return the absolute value of this UnitDbl."""
return UnitDbl( abs( self._value ), self._units )
#-----------------------------------------------------------------------
def __neg__( self ):
"""Return the negative value of this UnitDbl."""
return UnitDbl( -self._value, self._units )
#-----------------------------------------------------------------------
def __nonzero__( self ):
"""Test a UnitDbl for a non-zero value.
= RETURN VALUE
- Returns true if the value is non-zero.
"""
return self._value.__nonzero__()
#-----------------------------------------------------------------------
def __cmp__( self, rhs ):
"""Compare two UnitDbl's.
= ERROR CONDITIONS
- If the input rhs units are not the same as our units,
an error is thrown.
= INPUT VARIABLES
- rhs The UnitDbl to compare against.
= RETURN VALUE
- Returns -1 if self < rhs, 0 if self == rhs, +1 if self > rhs.
"""
self.checkSameUnits( rhs, "compare" )
return cmp( self._value, rhs._value )
#-----------------------------------------------------------------------
def __add__( self, rhs ):
"""Add two UnitDbl's.
= ERROR CONDITIONS
- If the input rhs units are not the same as our units,
an error is thrown.
= INPUT VARIABLES
- rhs The UnitDbl to add.
= RETURN VALUE
- Returns the sum of ourselves and the input UnitDbl.
"""
self.checkSameUnits( rhs, "add" )
return UnitDbl( self._value + rhs._value, self._units )
#-----------------------------------------------------------------------
def __sub__( self, rhs ):
"""Subtract two UnitDbl's.
= ERROR CONDITIONS
- If the input rhs units are not the same as our units,
an error is thrown.
= INPUT VARIABLES
- rhs The UnitDbl to subtract.
= RETURN VALUE
- Returns the difference of ourselves and the input UnitDbl.
"""
self.checkSameUnits( rhs, "subtract" )
return UnitDbl( self._value - rhs._value, self._units )
#-----------------------------------------------------------------------
def __mul__( self, rhs ):
"""Scale a UnitDbl by a value.
= INPUT VARIABLES
- rhs The scalar to multiply by.
= RETURN VALUE
- Returns the scaled UnitDbl.
"""
return UnitDbl( self._value * rhs, self._units )
#-----------------------------------------------------------------------
def __rmul__( self, lhs ):
"""Scale a UnitDbl by a value.
= INPUT VARIABLES
- lhs The scalar to multiply by.
= RETURN VALUE
- Returns the scaled UnitDbl.
"""
return UnitDbl( self._value * lhs, self._units )
#-----------------------------------------------------------------------
def __div__( self, rhs ):
"""Divide a UnitDbl by a value.
= INPUT VARIABLES
- rhs The scalar to divide by.
= RETURN VALUE
- Returns the scaled UnitDbl.
"""
return UnitDbl( self._value / rhs, self._units )
#-----------------------------------------------------------------------
def __str__( self ):
"""Print the UnitDbl."""
return "%g *%s" % ( self._value, self._units )
#-----------------------------------------------------------------------
def __repr__( self ):
"""Print the UnitDbl."""
return "UnitDbl( %g, '%s' )" % ( self._value, self._units )
#-----------------------------------------------------------------------
def type( self ):
"""Return the type of UnitDbl data."""
return self._types[ self._units ]
#-----------------------------------------------------------------------
def range( start, stop, step=None ):
"""Generate a range of UnitDbl objects.
Similar to the Python range() method. Returns the range [
start, stop ) at the requested step. Each element will be a
UnitDbl object.
= INPUT VARIABLES
- start The starting value of the range.
- stop The stop value of the range.
- step Optional step to use. If set to None, then a UnitDbl of
value 1 w/ the units of the start is used.
= RETURN VALUE
- Returns a list contianing the requested UnitDbl values.
"""
if step is None:
step = UnitDbl( 1, start._units )
elems = []
i = 0
while True:
d = start + i * step
if d >= stop:
break
elems.append( d )
i += 1
return elems
range = staticmethod( range )
#-----------------------------------------------------------------------
def checkUnits( self, units ):
"""Check to see if some units are valid.
= ERROR CONDITIONS
- If the input units are not in the allowed list, an error is thrown.
= INPUT VARIABLES
- units The string name of the units to check.
"""
if units not in self.allowed.keys():
msg = "Input units '%s' are not one of the supported types of %s" \
% ( units, str( self.allowed.keys() ) )
raise ValueError( msg )
#-----------------------------------------------------------------------
def checkSameUnits( self, rhs, func ):
"""Check to see if units are the same.
= ERROR CONDITIONS
- If the units of the rhs UnitDbl are not the same as our units,
an error is thrown.
= INPUT VARIABLES
- rhs The UnitDbl to check for the same units
- func The name of the function doing the check.
"""
if self._units != rhs._units:
msg = "Cannot %s units of different types.\n" \
"LHS: %s\n" \
"RHS: %s" % ( func, self._units, rhs._units )
raise ValueError( msg )
#===========================================================================