Add round method to checks base #2931
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@@ Coverage Diff @@
## master #2931 +/- ##
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- Coverage 84.79% 75.5% -9.29%
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Files 649 45 -604
Lines 36097 3572 -32525
Branches 4301 429 -3872
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- Hits 30608 2697 -27911
+ Misses 4215 766 -3449
+ Partials 1274 109 -1165 |
| @@ -23,6 +24,11 @@ def ensure_unicode(s): | |||
| to_string = ensure_unicode if PY3 else ensure_bytes | |||
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| def round_value(value, sig_digits="0.01", rounding_method=ROUND_HALF_UP): | |||
| 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
| @@ -23,6 +24,11 @@ def ensure_unicode(s): | |||
| to_string = ensure_unicode if PY3 else ensure_bytes | |||
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| 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 🙂
| @@ -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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| from decimal import ROUND_HALF_UP, Decimal, getcontext | |
| from decimal import ROUND_HALF_UP, Decimal |
| @@ -23,6 +24,11 @@ def ensure_unicode(s): | |||
| to_string = ensure_unicode if PY3 else ensure_bytes | |||
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| def round_value(value, sig_digits="0.01", rounding_method=ROUND_HALF_UP): | |||
| getcontext().rounding = rounding_method | |||
| return float(Decimal(str(value)).quantize(Decimal(sig_digits))) | |||
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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!
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| class TestRounding(): | ||
| def test_round_half_up(self): | ||
| assert round_value(2.555) == 2.560 |
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| assert round_value(2.555) == 2.560 | |
| assert round_num(2.5) == 3 |
What does this PR do?
Creates a rounding util method in checks_base that should mostly adhere to how
roundworked in Py2Motivation
Python2 and 3 use different rounding strategies and could offer different results. Python 2, in the event of a tie, rounds away from zero.
Python 3 on the other hand, breaks the tie by rounding to the closer even number
Ex:
Py2: round(2.5) -> 3
Py3: round(2.5) -> 2
Using the Decimal library allows us to control the rounding strategy and keeps all checks using the
roundfunction able to return the same value as before.Review checklist
no-changeloglabel attachedAdditional Notes
Anything else we should know when reviewing?