v0.19.1 (November 3, 2016)

This is a minor bug-fix release from 0.19.0 and includes some small regression fixes, bug fixes and performance improvements. We recommend that all users upgrade to this version.

Performance Improvements

• Fixed performance regression in factorization of Period data (GH14338)
• Fixed performance regression in Series.asof(where) when where is a scalar (GH14461)
• Improved performance in DataFrame.asof(where) when where is a scalar (GH14461)
• Improved performance in .to_json() when lines=True (GH14408)
• Improved performance in certain types of loc indexing with a MultiIndex (GH14551).

Bug Fixes

• Source installs from PyPI will now again work without cython installed, as in previous versions (GH14204)
• Compat with Cython 0.25 for building (GH14496)
• Fixed regression where user-provided file handles were closed in read_csv (c engine) (GH14418).
• Fixed regression in DataFrame.quantile when missing values where present in some columns (GH14357).
• Fixed regression in Index.difference where the freq of a DatetimeIndex was incorrectly set (GH14323)
• Added back pandas.core.common.array_equivalent with a deprecation warning (GH14555).
• Bug in pd.read_csv for the C engine in which quotation marks were improperly parsed in skipped rows (GH14459)
• Bug in pd.read_csv for Python 2.x in which Unicode quote characters were no longer being respected (GH14477)
• Fixed regression in Index.append when categorical indices were appended (GH14545).
• Fixed regression in pd.DataFrame where constructor fails when given dict with None value (GH14381)
• Fixed regression in DatetimeIndex._maybe_cast_slice_bound when index is empty (GH14354).
• Bug in localizing an ambiguous timezone when a boolean is passed (GH14402)
• Bug in TimedeltaIndex addition with a Datetime-like object where addition overflow in the negative direction was not being caught (GH14068, GH14453)
• Bug in string indexing against data with object Index may raise AttributeError (GH14424)
• Correctly raise ValueError on empty input to pd.eval() and df.query() (GH13139)
• Bug in RangeIndex.intersection when result is a empty set (GH14364).
• Bug in groupby-transform broadcasting that could cause incorrect dtype coercion (GH14457)
• Bug in Series.__setitem__ which allowed mutating read-only arrays (GH14359).
• Bug in DataFrame.insert where multiple calls with duplicate columns can fail (GH14291)
• pd.merge() will raise ValueError with non-boolean parameters in passed boolean type arguments (GH14434)
• Bug in Timestamp where dates very near the minimum (1677-09) could underflow on creation (GH14415)
• Bug in pd.concat where names of the keys were not propagated to the resulting MultiIndex (GH14252)
• Bug in pd.concat where axis cannot take string parameters 'rows' or 'columns' (GH14369)
• Bug in pd.concat with dataframes heterogeneous in length and tuple keys (GH14438)
• Bug in MultiIndex.set_levels where illegal level values were still set after raising an error (GH13754)
• Bug in DataFrame.to_json where lines=True and a value contained a } character (GH14391)
• Bug in df.groupby causing an AttributeError when grouping a single index frame by a column and the index level (GH14327)
• Bug in df.groupby where TypeError raised when pd.Grouper(key=...) is passed in a list (GH14334)
• Bug in pd.pivot_table may raise TypeError or ValueError when index or columns is not scalar and values is not specified (GH14380)

Contributors

A total of 30 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

• Adam Chainz +
• Anthonios Partheniou
• Arash Rouhani +
• Ben Kandel
• Brandon M. Burroughs +
• Chris
• Chris Warth
• David Krych +
• Iván Vallés Pérez +
• Jeff Reback
• Joe Jevnik
• Jon M. Mease +
• Jon Mease +
• Joris Van den Bossche
• Josh Owen +
• Keshav Ramaswamy +
• Larry Ren +
• Michael Felt +
• Piotr Chromiec +
• Robert Bradshaw +
• Sinhrks
• Thiago Serafim +
• Tom Bird
• bkandel +
• chris-b1
• dubourg +
• gfyoung
• mattrijk +
• paul-mannino +
• sinhrks