numpy.round(i, decimals=d) wrong for np.int64 and d<0
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00 - Bug
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- Python
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Description
numpy.round returns wrong value when decimals are negative and argument is np.int64
Reproducing code example:
>>> import numpy as np
>>> np.round(2**63-1, -3)
-9223372036854775808
>>> round(2**63-1, -3)
9223372036854776000
Numpy/Python version information:
>>> import sys, numpy; print(numpy.__version__, sys.version)
1.15.1 3.6.5 (default, Apr 5 2018, 23:36:52)
[GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.1)]
Contributor guide
First steps
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- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the issue through numpy.round with an np.int64 value near the upper integer limit and a negative decimals value, then compare it with Python's round. Confirm the behavior across relevant negative decimal values and add regression coverage showing that rounding does not produce the incorrect wrapped result.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- numpy, python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100