Python decimal.ROUND_HALF_EVEN Examples

def round(number, ndigits=None):
        return_int = False
        if ndigits is None:
            return_int = True
            ndigits = 0
        if hasattr(number, '__round__'):
            return number.__round__(ndigits)

        if ndigits < 0:
            raise NotImplementedError('negative ndigits not supported yet')
        exponent = Decimal('10') ** (-ndigits)
        d = Decimal.from_float(number).quantize(exponent,
                                                rounding=ROUND_HALF_EVEN)
        if return_int:
            return int(d)
        else:
            return float(d) 

def calculate_price(base_quantity, quote_quantity, base_divisibility, quote_divisibility, order_type=None):
    if not base_divisibility:
        base_quantity *= config.UNIT
    if not quote_divisibility:
        quote_quantity *= config.UNIT

    try:
        if order_type == 'BUY':
            decimal.setcontext(decimal.Context(prec=8, rounding=decimal.ROUND_DOWN))
        elif order_type == 'SELL':
            decimal.setcontext(decimal.Context(prec=8, rounding=decimal.ROUND_UP))

        price = format(D(quote_quantity) / D(base_quantity), '.8f')

        decimal.setcontext(decimal.Context(prec=8, rounding=decimal.ROUND_HALF_EVEN))
        return price

    except Exception as e:
        logging.exception(e)
        decimal.setcontext(decimal.Context(prec=8, rounding=decimal.ROUND_HALF_EVEN))
        raise(e) 

def move(self, fromaccount, toaccount, amount, minconf=1):
        """Send coins between accounts in the same wallet.

        If the receiving account does not exist, it is automatically
        created (but not automatically assigned an address).

        Args:
          fromaccount (str): origin account
          toaccount (str): destination account
          amount (str or Decimal): amount to send (8 decimal points)
          minconf (int): ensure the account has a valid balance using this
                         many confirmations (default=1) 

        Returns:
          bool: True if the coins are moved successfully, False otherwise

        """
        amount = Decimal(amount).quantize(self.quantum, rounding=ROUND_HALF_EVEN)
        return self.rpc.call("move",
            fromaccount, toaccount, float(str(amount)), minconf
        ) 

def sendfrom(self, user_id, dest_address, amount, minconf=1):
        """
        Send coins from user's account.

        Args:
          user_id (str): this user's unique identifier
          dest_address (str): address which is to receive coins
          amount (str or Decimal): amount to send (eight decimal points)
          minconf (int): ensure the account has a valid balance using this
                         many confirmations (default=1)

        Returns:
          str: transaction ID

        """
        amount = Decimal(amount).quantize(self.quantum, rounding=ROUND_HALF_EVEN)
        txhash = self.rpc.call("sendfrom",
            user_id, dest_address, float(str(amount)), minconf
        )
        self.logger.debug("Send %s %s from %s to %s" % (str(amount), self.coin,
                                                        str(user_id), dest_address))
        self.logger.debug("Transaction hash: %s" % txhash)
        return txhash 

def setUp(self):
        self.user_id = "testaccount1"
        self.other_user_id = "testaccount2"
        self.coin = "Bitcoin"
        self.message = "hello world!"   # used for signature testing
        self.txfields = ("account", "category", "amount", "time")
        self.quantum = Decimal("1e-"+str(COINS[self.coin.lower()]["decimals"]))
        self.amount_to_send = Decimal("0.01").quantize(self.quantum,
                                                       rounding=ROUND_HALF_EVEN)
        self.txfee = Decimal(COINS[self.coin.lower()]["txfee"])
        self.bridge = Bridge(coin=self.coin, testnet=True,
                             reconnect=False, testing=True)
        self.assertFalse(self.bridge.reconnect)
        self.assertEqual(self.bridge.quantum, self.quantum)
        self.assertTrue(self.bridge.testnet)
        self.assertEqual(self.bridge.coin, u"bitcoin")
        self.assertTrue(self.bridge.connected)
        self.user_address = self.bridge.getaccountaddress(self.user_id)
        self.other_user_address = self.bridge.getaccountaddress(self.other_user_id)
        self.bridge.walletlock()
        self.btc_testnet_faucet = "msj42CCGruhRsFrGATiUuh25dtxYtnpbTx" 

def setUp(self):
        self.user_id = "testaccount1"
        self.other_user_id = "testaccount2"
        self.coin = "Bitcoin"
        self.message = "hello world!"   # used for signature testing
        self.txfields = ("account", "category", "amount", "time")
        self.quantum = Decimal("1e-"+str(COINS[self.coin.lower()]["decimals"]))
        self.amount_to_send = Decimal("0.01").quantize(self.quantum,
                                                       rounding=ROUND_HALF_EVEN)
        self.txfee = Decimal(COINS[self.coin.lower()]["txfee"])
        self.bridge = Bridge(coin=self.coin, testnet=True,
                             reconnect=False, testing=True)
        self.assertFalse(self.bridge.reconnect)
        self.assertEqual(self.bridge.quantum, self.quantum)
        self.assertTrue(self.bridge.testnet)
        self.assertEqual(self.bridge.coin, u"bitcoin")
        self.assertTrue(self.bridge.connected)
        self.user_address = self.bridge.getaccountaddress(self.user_id)
        self.other_user_address = self.bridge.getaccountaddress(self.other_user_id)
        self.bridge.walletlock()
        self.btc_testnet_faucet = "msj42CCGruhRsFrGATiUuh25dtxYtnpbTx" 

def _round_quantize(self, val):

        # round() has different behavior in python 2/3
        # For consistency between 2 and 3 we use quantize, however
        # it is slower than the built in round function.
        d = decimal.Decimal(val)
        rounded = d.quantize(1, rounding=decimal.ROUND_HALF_EVEN)
        return float(rounded) 

def pydecimal_equivalent_rounding_mode(self):
        return {
            RM.RM_TowardsPositiveInf:      decimal.ROUND_CEILING,
            RM.RM_TowardsNegativeInf:      decimal.ROUND_FLOOR,
            RM.RM_TowardsZero:             decimal.ROUND_DOWN,
            RM.RM_NearestTiesEven:         decimal.ROUND_HALF_EVEN,
            RM.RM_NearestTiesAwayFromZero: decimal.ROUND_UP,
        }[self] 

def _round_quantize(self, val):

        # round() has different behavior in python 2/3
        # For consistency between 2 and 3 we use quantize, however
        # it is slower than the built in round function.
        d = decimal.Decimal(val)
        rounded = d.quantize(1, rounding=decimal.ROUND_HALF_EVEN)
        return float(rounded) 

def f2s(self, f):
        return str(dec.Decimal(repr(f)).quantize(self.car_prec, dec.ROUND_HALF_EVEN)) 

def intround(value):
    """Given a float returns a rounded int. Should give the same result on
    both Py2/3
    """

    return int(decimal.Decimal.from_float(
        value).to_integral_value(decimal.ROUND_HALF_EVEN)) 

def banker_round(decimal_value):
    """
    Force the value to be rounded with the `ROUND_HALF_EVEN` method,
    also called the Banking Rounding due to the heavy use in the
    banking system
    """
    return decimal_value.quantize(decimal.Decimal('0.01'),
                                  rounding=decimal.ROUND_HALF_EVEN) 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.

    Delegates to the __round__ method if for some reason this exists.

    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.

    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)

    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if isinstance(number, Decimal):
        d = number
    else:
        if not PY26:
            d = Decimal.from_float(number).quantize(exponent,
                                                rounding=ROUND_HALF_EVEN)
        else:
            d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)


### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.

    Delegates to the __round__ method if for some reason this exists.

    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.

    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)

    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if isinstance(number, Decimal):
        d = number
    else:
        if not PY26:
            d = Decimal.from_float(number).quantize(exponent,
                                                rounding=ROUND_HALF_EVEN)
        else:
            d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)


### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.

    Delegates to the __round__ method if for some reason this exists.

    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.

    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)

    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if isinstance(number, Decimal):
        d = number
    else:
        if not PY26:
            d = Decimal.from_float(number).quantize(exponent,
                                                rounding=ROUND_HALF_EVEN)
        else:
            d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)


### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.

    Delegates to the __round__ method if for some reason this exists.

    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.

    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)

    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)


### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.

    Delegates to the __round__ method if for some reason this exists.

    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.

    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)

    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)


### From Python 2.7's decimal.py. Only needed to support Py2.6: 

def newround(number, ndigits=None):
    """
    See Python 3 documentation: uses Banker's Rounding.
 
    Delegates to the __round__ method if for some reason this exists.
 
    If not, rounds a number to a given precision in decimal digits (default
    0 digits). This returns an int when called with one argument,
    otherwise the same type as the number. ndigits may be negative.
 
    See the test_round method in future/tests/test_builtins.py for
    examples.
    """
    return_int = False
    if ndigits is None:
        return_int = True
        ndigits = 0
    if hasattr(number, '__round__'):
        return number.__round__(ndigits)
    
    if ndigits < 0:
        raise NotImplementedError('negative ndigits not supported yet')
    exponent = Decimal('10') ** (-ndigits)

    if PYPY:
        # Work around issue #24: round() breaks on PyPy with NumPy's types
        if 'numpy' in repr(type(number)):
            number = float(number)

    if not PY26:
        d = Decimal.from_float(number).quantize(exponent,
                                            rounding=ROUND_HALF_EVEN)
    else:
        d = from_float_26(number).quantize(exponent, rounding=ROUND_HALF_EVEN)

    if return_int:
        return int(d)
    else:
        return float(d)
 

### From Python 2.7's decimal.py. Only needed to support Py2.6: