Version 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)

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

A total of 9 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.