Holoviews

**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).

**June 27, 2015**

Since the last release we closed over 34 issues and have made 380
commits mostly focused on fixing bugs, cleaning up the API and working
extensively on the plotting and rendering system to ensure HoloViews is
fully backend independent.

We'd again like to thank our growing user base for all their input,
which has helped us in making the API more understandable and fixing a
number of important bugs.

Highlights/Features:

- Allowed display of data structures which do not match the
recommended nesting hierarchy (67b28f3, fbd89c3).
- Dimensions now sanitized for `.select`, `.sample` and `.reduce`
calls (6685633, 00b5a66).
- Added `holoviews.ipython.display` function to render (and display)
any HoloViews object, useful for IPython interact widgets (0fa49cd).
- Table column widths now adapt to cell contents (be90a54).
- Defaulting to Matplotlib ticking behavior (62e1e58).
- Allowed specifying fixed figure sizes to Matplotlib via `fig_inches`
tuples using (width, None) and (None, height) formats (632facd).
- Constructors of `Chart`, `Path` and `Histogram` classes now support
additional data formats (2297375).
- `ScrubberWidget` now supports all figure formats (c317db4).
- Allowed customizing legend positions on `Bars` Elements (5a12882).
- Support for multiple colorbars on one axis (aac7b92).
- `.reindex` on `NdElement` types now support converting between key
and value dimensions allowing more powerful conversions. (03ac3ce)
- Improved support for casting between `Element` types (cdaab4e,
b2ad91b, ce7fe2d, 865b4d5).
- The `%%opts` cell magic may now be used multiple times in the same
cell (2a77fd0)
- Matplotlib rcParams can now be set correctly per figure (751210f).
- Improved `OptionTree` repr which now works with eval (2f824c1).
- Refactor of rendering system and IPython extension to allow easy
swapping of plotting backend (\141)
- Large plotting optimization by computing tight `bbox_inches`
once (e34e339).
- Widgets now cache frames in the DOM, avoiding flickering in some
browsers and make use of jinja2 template inheritance. (fc7dd2b)
- Calling a HoloViews object without arguments now clears any
associated custom styles. (9e8c343)

API Changes

- Renamed key_dimensions and value_dimensions to kdims and vdims
respectively, while providing backward compatibility for passing and
accessing the long names (8feb7d2).
- Combined x/y/zticker plot options into x/y/zticks parameters which
now accept an explicit number of ticks, an explicit list of tick
positions (and labels), and a Matplotlib tick locator.
- Changed backend options in %output magic, `nbagg` and `d3` are now
modes of the Matplotlib backend and can be selected with
`backend='matplotlib:nbagg'` and
`backend='matplotlib:mpld3'` respectively. The 'd3' and 'nbagg'
options remain supported but will be deprecated in future.
- Customizations should no longer be applied directly to
`Store.options`; the `Store.options(backend='matplotlib')` object
should be customized instead. There is no longer a need to call the
deprecated `Store.register_plots` method.