Holoviews

**December 22, 2015**

Over the past two weeks since the 1.4 release, we have implemented
several important bug fixes and have made several usability
improvements.

New features:

- Improved help system. It is now possible to recursively list all the
applicable documentation for a composite object. In addition, the
documentation may now be filtered using a regular
expression pattern. ([PR
\370](https://github.com/pyviz/holoviews/pull/370))
- HoloViews now supports multiple active display hooks making it
easier to use nbconvert. For instance, PNG data will be embedded in
the notebook if the argument display_formats=\['html','png'\] is
supplied to the notebook_extension. ([PR
\355](https://github.com/pyviz/holoviews/pull/355))
- Improvements to the display of DynamicMaps as well as many new
improvements to the Bokeh backend including better VLines/HLines and
support for the Bars element. ([PR
\367](https://github.com/pyviz/holoviews/pull/367) , [PR
\362](https://github.com/pyviz/holoviews/pull/362), [PR
\339](https://github.com/pyviz/holoviews/pull/339)).
- New Spikes and BoxWhisker elements suitable for representing
distributions as a sequence of lines or as a box-and-whisker plot.
([PR \346](https://github.com/pyviz/holoviews/pull/346), [PR
\339](https://github.com/pyviz/holoviews/pull/339))
- Improvements to the notebook_extension. For instance,
executing hv.notebook_extension('bokeh') will now load BokehJS and
automatically activate the Bokeh backend (if available).
- Significant performance improvements when using the groupby
operation on HoloMaps and when working with highly
nested datastructures. ([PR
\349](https://github.com/pyviz/holoviews/pull/349), [PR
\359](https://github.com/pyviz/holoviews/pull/359))

Notable bug fixes:

- DynamicMaps are now properly integrated into the style system and
can be customized in the same way as HoloMaps. ([PR
\368](https://github.com/pyviz/holoviews/pull/368))
- Widgets now work correctly when unicode is used in the dimension
labels and values ([PR
\376](https://github.com/pyviz/holoviews/pull/376)).

**December 4, 2015**

Over the past few months we have added several major new features and
with the help of our users have been able to address a number of bugs
and inconsistencies. We have closed 57 issues and added over 1100 new
commits.

Major new features:

- Data API: The new data API brings an extensible system of to add new
data interfaces to column based Element types. These interfaces
allow applying powerful operations on the data independently of the
data format. The currently supported datatypes include NumPy, pandas
dataframes and a simple dictionary format. ([PR
\284](https://github.com/pyviz/holoviews/pull/284))
- Backend API: In this release we completely refactored the rendering,
plotting and IPython display system to make it easy to add new
plotting backends. Data may be styled and pickled for each backend
independently and renderers now support exporting all plotting data
including widgets as standalone HTML files or with separate
JSON data.
- Bokeh backend: The first new plotting backend added via the new
backend API. Bokeh plots allow for much faster plotting and
greater interactivity. Supports most Element types and layouts and
provides facilities for sharing axes across plots and linked
brushing across plots. ([PR
\250](https://github.com/pyviz/holoviews/pull/250))
- DynamicMap: The new DynamicMap class allows HoloMap data to be
generated on-the-fly while running a Jupyter IPython
notebook kernel. Allows visualization of unbounded data streams and
smooth exploration of large continuous parameter spaces. ([PR
\278](https://github.com/pyviz/holoviews/pull/278))

Other features:

- Easy definition of custom aliases for group, label and Dimension
names, allowing easier use of LaTeX.
- New Trisurface and QuadMesh elements.
- Widgets now allow expressing hierarchical relationships
between dimensions.
- Added GridMatrix container for heterogeneous Elements and gridmatrix
operation to generate scatter matrix showing relationship
between dimensions.
- Filled contour regions can now be generated using the
contours operation.
- Consistent indexing semantics for all Elements and support for
boolean indexing for Columns and NdMapping types.
- New hv.notebook_extension function offers a more flexible
alternative to %load_ext, e.g. for loading other
extensions hv.notebook_extension(bokeh=True).

Experimental features:

- Bokeh callbacks allow adding interactivity by communicating between
BokehJS tools and the IPython kernel, e.g. allowing downsampling
based on the zoom level.

Notable bug fixes:

- Major speedup rendering large HoloMaps (\~ 2-3 times faster).
- Colorbars now consistent for all plot configurations.
- Style pickling now works correctly.

API Changes:

- Dimension formatter parameter now deprecated in favor
of value_format.
- Types of Chart and Table Element data now dependent on
selected interface.
- DFrame conversion interface deprecated in favor of Columns
pandas interface.

**July 6, 2015**

Minor bugfix release to address a small number of issues:

Features:

- Added support for colorbars on Surface Element (1cd5281).
- Added linewidth style option to SurfacePlot (9b6ccc5).

Bug fixes:

- Fixed inversion inversion of y-range during sampling (6ff81bb).
- Fixed overlaying of 3D elements (787d511).
- Ensuring that underscore.js is loaded in widgets (f2f6378).
- Fixed Python3 issue in Overlay.get (8ceabe3).

**July 1, 2015**

Minor bugfix release to address a number of issues that weren't caught
in time for the 1.3.0 release with the addition of a small number of
features:

Features:

- Introduced new `Spread` element to plot errors and confidence
intervals (30d3184).
- `ErrorBars` and `Spread` elements now allow most Chart constructor
types (f013deb).

Bug fixes:

- Fixed unicode handling for dimension labels (061e9af).
- Handling of invalid dimension label characters in widgets (a101b9e).
- Fixed setting of fps option for MPLRenderer video output (c61b9df).
- Fix for multiple and animated colorbars (5e1e4b5).
- Fix to Chart slices starting or ending at zero (edd0039).