v0.19.0 (October 2, 2016)¶
This is a major release from 0.18.1 and includes number of API changes, several new features, enhancements, and performance improvements along with a large number of bug fixes. We recommend that all users upgrade to this version.
Highlights include:
merge_asof()
for asof-style time-series joining, see here.rolling()
is now time-series aware, see hereread_csv()
now supports parsingCategorical
data, see here- A function
union_categorical()
has been added for combining categoricals, see here PeriodIndex
now has its ownperiod
dtype, and changed to be more consistent with otherIndex
classes. See here- Sparse data structures gained enhanced support of
int
andbool
dtypes, see here - Comparison operations with
Series
no longer ignores the index, see here for an overview of the API changes. - Introduction of a pandas development API for utility functions, see here.
- Deprecation of
Panel4D
andPanelND
. We recommend to represent these types of n-dimensional data with the xarray package. - Removal of the previously deprecated modules
pandas.io.data
,pandas.io.wb
,pandas.tools.rplot
.
Warning
pandas >= 0.19.0 will no longer silence numpy ufunc warnings upon import, see here.
What’s new in v0.19.0
- New features
merge_asof
for asof-style time-series joining.rolling()
is now time-series awareread_csv
has improved support for duplicate column namesread_csv
supports parsingCategorical
directly- Categorical Concatenation
- Semi-Month Offsets
- New Index methods
- Google BigQuery Enhancements
- Fine-grained numpy errstate
get_dummies
now returns integer dtypes- Downcast values to smallest possible dtype in
to_numeric
- pandas development API
- Other enhancements
- API changes
Series.tolist()
will now return Python typesSeries
operators for different indexesSeries
type promotion on assignment.to_datetime()
changes- Merging changes
.describe()
changesPeriod
changes- Index
+
/-
no longer used for set operations Index.difference
and.symmetric_difference
changesIndex.unique
consistently returnsIndex
MultiIndex
constructors,groupby
andset_index
preserve categorical dtypesread_csv
will progressively enumerate chunks- Sparse Changes
- Indexer dtype changes
- Other API Changes
- Deprecations
- Removal of prior version deprecations/changes
- Performance Improvements
- Bug Fixes
- Contributors
New features¶
merge_asof
for asof-style time-series joining¶
A long-time requested feature has been added through the merge_asof()
function, to
support asof style joining of time-series (GH1870, GH13695, GH13709, GH13902). Full documentation is
here.
The merge_asof()
performs an asof merge, which is similar to a left-join
except that we match on nearest key rather than equal keys.
In [1]: left = pd.DataFrame({'a': [1, 5, 10],
...: 'left_val': ['a', 'b', 'c']})
...:
In [2]: right = pd.DataFrame({'a': [1, 2, 3, 6, 7],
...: 'right_val': [1, 2, 3, 6, 7]})
...:
In [3]: left
Out[3]:
a left_val
0 1 a
1 5 b
2 10 c
[3 rows x 2 columns]
In [4]: right