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Add round method to checks base #2931

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Jan 14, 2019
Merged

Add round method to checks base #2931

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a9a1f34
Add rounding util
nmuesch Jan 11, 2019
f436c9a
Add rounding method to checks base
nmuesch Jan 11, 2019
2e191a3
Address review
nmuesch Jan 11, 2019
8346e93
Cleanup
nmuesch Jan 11, 2019
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6 changes: 6 additions & 0 deletions datadog_checks_base/datadog_checks/base/utils/common.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
# (C) Datadog, Inc. 2018
# All rights reserved
# Licensed under a 3-clause BSD style license (see LICENSE)
from decimal import ROUND_HALF_UP, Decimal, getcontext
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Suggested change
from decimal import ROUND_HALF_UP, Decimal, getcontext
from decimal import ROUND_HALF_UP, Decimal

import os
import re

Expand All @@ -23,6 +24,11 @@ def ensure_unicode(s):
to_string = ensure_unicode if PY3 else ensure_bytes


def round_value(value, sig_digits="0.01", rounding_method=ROUND_HALF_UP):
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same here, sig_digits can be a float.

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same consideration as above 🙂

getcontext().rounding = rounding_method
return float(Decimal(str(value)).quantize(Decimal(sig_digits)))
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no need to convert to string before passing to decimal

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You do actually to get proper arithmetic

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Yeah, there are interesting behaviors when you don't appropriately cast to string. The documentation for Decimal also has all floating point examples in string format - https://docs.python.org/2/library/decimal.html

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def round_num(value, precision=0):
    return float(Decimal(str(value)).quantize(Decimal('0.{}'.format('0' * precision)), rounding=ROUND_HALF_UP))

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I like leaving it open to modify the rounding strategy if anyone requires something like Python 3s ROUND_HALF_EVEN function later. I don't think it hurts to leave it in the signature as an optional parameter

I do like the precision component!



def get_docker_hostname():
return urlparse(os.getenv('DOCKER_HOST', '')).hostname or 'localhost'

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17 changes: 16 additions & 1 deletion datadog_checks_base/tests/test_utils.py
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Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
# (C) Datadog, Inc. 2018
# All rights reserved
# Licensed under a 3-clause BSD style license (see LICENSE)
from decimal import ROUND_HALF_DOWN, ROUND_HALF_UP

from datadog_checks.utils.common import pattern_filter
from datadog_checks.utils.common import pattern_filter, round_value
from datadog_checks.utils.limiter import Limiter


Expand Down Expand Up @@ -105,3 +106,17 @@ def test_reset(self):
assert limiter.get_status() == (0, 10, False)
assert limiter.is_reached("dummy1") is False
assert limiter.get_status() == (1, 10, False)


class TestRounding():
def test_round_half_up(self):
assert round_value(2.555) == 2.560
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Suggested change
assert round_value(2.555) == 2.560
assert round_num(2.5) == 3


def test_round_modify_method(self):
assert round_value(3.5, sig_digits="1", rounding_method=ROUND_HALF_DOWN) == 3.0

def test_round_modify_sig_digits(self):
assert round_value(3.5, sig_digits="1") == 4.0
assert round_value(2.555, sig_digits="0.01") == 2.560
assert round_value(4.2345, sig_digits="0.01") == 4.23
assert round_value(4.2345, sig_digits="0.000") == 4.235