# NumPy 1.16.4 Release Notes

The NumPy 1.16.4 release fixes bugs reported against the 1.16.3 release, and also backports several enhancements from master that seem appropriate for a release series that is the last to support Python 2.7. The wheels on PyPI are linked with OpenBLAS v0.3.7-dev, which should fix issues on Skylake series cpus.

Downstream developers building this release should use Cython >= 0.29.2 and, if using OpenBLAS, OpenBLAS > v0.3.7. The supported Python versions are 2.7 and 3.5-3.7.

## New deprecations

### Writeable flag of C-API wrapped arrays

When an array is created from the C-API to wrap a pointer to data, the only indication we have of the read-write nature of the data is the `writeable` flag set during creation. It is dangerous to force the flag to writeable. In the future it will not be possible to switch the writeable flag to `True` from python. This deprecation should not affect many users since arrays created in such a manner are very rare in practice and only available through the NumPy C-API.

## Compatibility notes

### Potential changes to the random stream

Due to bugs in the application of log to random floating point numbers, the stream may change when sampling from `np.random.beta`, `np.random.binomial`, `np.random.laplace`, `np.random.logistic`, `np.random.logseries` or `np.random.multinomial` if a 0 is generated in the underlying MT19937 random stream. There is a 1 in \(10^{53}\) chance of this occurring, and so the probability that the stream changes for any given seed is extremely small. If a 0 is encountered in the underlying generator, then the incorrect value produced (either `np.inf` or `np.nan`) is now dropped.

## Changes

### `numpy.lib.recfunctions.structured_to_unstructured` does not squeeze single-field views

Previously `structured_to_unstructured(arr[['a']])` would produce a squeezed result inconsistent with `structured_to_unstructured(arr[['a', b']])`. This was accidental. The old behavior can be retained with `structured_to_unstructured(arr[['a']]).squeeze(axis=-1)` or far more simply, `arr['a']`.

## Contributors

A total of 10 people contributed to this release. People with a “+” by their names contributed a patch for the first time.

- Charles Harris

- Eric Wieser

- Dennis Zollo +

- Hunter Damron +

- Jingbei Li +

- Kevin Sheppard

- Matti Picus

- Nicola Soranzo +

- Sebastian Berg

- Tyler Reddy

## Pull requests merged

A total of 16 pull requests were merged for this release.

- #13392: BUG: Some PyPy versions lack PyStructSequence_InitType2.

- #13394: MAINT, DEP: Fix deprecated `assertEquals()`

- #13396: BUG: Fix structured_to_unstructured on single-field types (backport)

- #13549: BLD: Make CI pass again with pytest 4.5

- #13552: TST: Register markers in conftest.py.

- #13559: BUG: Removes ValueError for empty kwargs in arraymultiter_new

- #13560: BUG: Add TypeError to accepted exceptions in crackfortran.

- #13561: BUG: Handle subarrays in descr_to_dtype

- #13562: BUG: Protect generators from log(0.0)

- #13563: BUG: Always return views from structured_to_unstructured when…

- #13564: BUG: Catch stderr when checking compiler version

- #13565: BUG: longdouble(int) does not work

- #13587: BUG: distutils/system_info.py fix missing subprocess import (#13523)

- #13620: BUG,DEP: Fix writeable flag setting for arrays without base

- #13641: MAINT: Prepare for the 1.16.4 release.

- #13644: BUG: special case object arrays when printing rel-, abs-error

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