# Version 0.6.1 (December 13, 2011)

## New features

- Can append single rows (as Series) to a DataFrame

- Add Spearman and Kendall rank correlation options to Series.corr and DataFrame.corr (GH428)

- Added `get_value` and `set_value` methods to Series, DataFrame, and Panel for very low-overhead access (>2x faster in many cases) to scalar elements (GH437, GH438). `set_value` is capable of producing an enlarged object.

- Add PyQt table widget to sandbox (GH435)

- DataFrame.align can accept Series arguments and an axis option (GH461)

- Implement new SparseArray and `SparseList` data structures. SparseSeries now derives from SparseArray (GH463)

- Better console printing options (GH453)

- Implement fast data ranking for Series and DataFrame, fast versions of scipy.stats.rankdata (GH428)

- Implement `DataFrame.from_items` alternate constructor (GH444)

- DataFrame.convert_objects method for inferring better dtypes for object columns (GH302)

- Add rolling_corr_pairwise function for computing Panel of correlation matrices (GH189)

- Add margins option to pivot_table for computing subgroup aggregates (GH114)

- Add `Series.from_csv` function (GH482)

- Can pass DataFrame/DataFrame and DataFrame/Series to rolling_corr/rolling_cov (GH #462)

- MultiIndex.get_level_values can accept the level name

## Performance improvements

- Improve memory usage of `DataFrame.describe` (do not copy data unnecessarily) (PR #425)

- Optimize scalar value lookups in the general case by 25% or more in Series and DataFrame

- Fix performance regression in cross-sectional count in DataFrame, affecting DataFrame.dropna speed

- Column deletion in DataFrame copies no data (computes views on blocks) (GH #158)

## Contributors

For contributors, please see /usr/share/doc/contributors_list.txt or https://github.com/pandas-dev/pandas/graphs/contributors