# v.0.5.0 (October 24, 2011)

## New features

- Added `DataFrame.align` method with standard join options
- Added `parse_dates` option to `read_csv` and `read_table` methods to optionally try to parse dates in the index columns
- Added `nrows`, `chunksize`, and `iterator` arguments to `read_csv` and `read_table`. The last two return a new `TextParser` class capable of lazily iterating through chunks of a flat file (GH242)
- Added ability to join on multiple columns in `DataFrame.join` (GH214)
- Added private `_get_duplicates` function to `Index` for identifying duplicate values more easily (ENH5c)
- Added column attribute access to DataFrame.
- Added Python tab completion hook for DataFrame columns. (GH233, GH230)
- Implemented `Series.describe` for Series containing objects (GH241)
- Added inner join option to `DataFrame.join` when joining on key(s) (GH248)
- Implemented selecting DataFrame columns by passing a list to `__getitem__` (GH253)
- Implemented & and | to intersect / union Index objects, respectively (GH261)
- Added `pivot_table` convenience function to pandas namespace (GH234)
- Implemented `Panel.rename_axis` function (GH243)
- DataFrame will show index level names in console output (GH334)
- Implemented `Panel.take`
- Added `set_eng_float_format` for alternate DataFrame floating point string formatting (ENH61)
- Added convenience `set_index` function for creating a DataFrame index from its existing columns
- Implemented `groupby` hierarchical index level name (GH223)
- Added support for different delimiters in `DataFrame.to_csv` (GH244)
- TODO: DOCS ABOUT TAKE METHODS

## Performance enhancements

- VBENCH Major performance improvements in file parsing functions `read_csv` and `read_table`
- VBENCH Added Cython function for converting tuples to ndarray very fast. Speeds up many MultiIndex-related operations
- VBENCH Refactored merging / joining code into a tidy class and disabled unnecessary computations in the float/object case, thus getting about 10% better performance (GH211)
- VBENCH Improved speed of `DataFrame.xs` on mixed-type DataFrame objects by about 5x, regression from 0.3.0 (GH215)
- VBENCH With new `DataFrame.align` method, speeding up binary operations between differently-indexed DataFrame objects by 10-25%.
- VBENCH Significantly sped up conversion of nested dict into DataFrame (GH212)
- VBENCH Significantly speed up DataFrame `__repr__` and `count` on large mixed-type DataFrame objects

## Contributors

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