. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 11 Merge, join, and concatenate 129 11.1 Concatenating objects . . . . . . . . . . . . . . . . . . . . . . . 2012) 1.2.1 New features • New unified merge function for efficiently performing full gamut of database / relational-algebra operations. Refactored existing join methods to use the new infrastructure, DataFrame.to_string • Can pass multiple DataFrames to DataFrame.join to join on index (GH115) • Can pass multiple Panels to Panel.join (GH115) • Added justify argument to DataFrame.to_string to allow

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 11 Merge, join, and concatenate 129 11.1 Concatenating objects . . . . . . . . . . . . . . . . . . . . . . . 2012) 1.3.1 New features • New unified merge function for efficiently performing full gamut of database / relational-algebra operations. Refactored existing join methods to use the new infrastructure, DataFrame.to_string • Can pass multiple DataFrames to DataFrame.join to join on index (GH115) • Can pass multiple Panels to Panel.join (GH115) • Added justify argument to DataFrame.to_string to allow

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 11 Merge, join, and concatenate 137 11.1 Concatenating objects . . . . . . . . . . . . . . . . . . . . . . . 2012) 1.4.1 New features • New unified merge function for efficiently performing full gamut of database / relational-algebra operations. Refactored existing join methods to use the new infrastructure, DataFrame.to_string • Can pass multiple DataFrames to DataFrame.join to join on index (GH115) • Can pass multiple Panels to Panel.join (GH115) • Added justify argument to DataFrame.to_string to allow

from previous page) 1 b 2 c 3 aaba 4 baca 5 NaN 6 caba 7 dog 8 cat dtype: object 3.2.6 Merge Concat pandas provides various facilities for easily combining together Series and DataFrame objects various kinds of set logic for the indexes and relational algebra functionality in the case of join / merge-type operations. See the Merging section. Concatenating pandas objects together with concat(): 172970 26 Chapter 3. Getting started pandas: powerful Python data analysis toolkit, Release 0.25.3 Join SQL style merges. See the Database style joining section. In [77]: left = pd.DataFrame({'key': ['foo'

comparison . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1.3.2.14 Index.intersection and inner join now preserve the order of the left Index . . . . . . 32 1.3.2.15 Pivot Table always returns a DataFrame features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.6.1.1 merge_asof for asof-style time-series joining . . . . . . . . . . . . . . . . . . . 53 1.6.1.2 .rolling() Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410 5.6 Merge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

comparison . . . . . . . . . . . . . . . . . . . . . . . . . . 61 1.5.2.14 Index.intersection and inner join now preserve the order of the left Index . . . . . . 61 1.5.2.15 Pivot Table always returns a DataFrame features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 1.8.1.1 merge_asof for asof-style time-series joining . . . . . . . . . . . . . . . . . . . 82 1.8.1.2 .rolling() Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 5.6 Merge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

comparison . . . . . . . . . . . . . . . . . . . . . . . . . . 30 1.2.2.14 Index.intersection and inner join now preserve the order of the left Index . . . . . . 31 1.2.2.15 Pivot Table always returns a DataFrame features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 1.5.1.1 merge_asof for asof-style time-series joining . . . . . . . . . . . . . . . . . . . 52 1.5.1.2 .rolling() Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408 5.6 Merge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 5.6 Merge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 6.7 Merge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 13 Merge, join, and concatenate 257 13.1 Concatenating objects . . . . . . . . . . . . . . . . . . . . . . .

non-existent columns will no longer reindex (GH17295) • Removed the previously deprecated keyword “join_axes” from concat(); use reindex_like on the result instead (GH22318) • Removed the previously deprecated blocks, Series.blocks (GH17656) • pandas.Series.str.cat() now defaults to aligning others, using join='left' (GH27611) • pandas.Series.str.cat() does not accept list-likes within list-likes anymore (GH27611) Categorical.astype() not allowing for casting to extension dtypes (GH28668) • Bug where merge() was unable to join on categorical and extension dtype columns (GH28668) • Categorical.searchsorted() and

column names with backticks to refer to names with spaces (GH6508) • merge_asof() now gives a more clear error message when merge keys are categoricals that are not equal (GH26136) • pandas.core.window to_timedelta(), pandas.Timedelta() and pandas.TimedeltaIndex() (GH16344) • pandas.concat() has deprecated the join_axes-keyword. Instead, use DataFrame.reindex() or DataFrame.reindex_like() on the result or on the (July 18, 2019) pandas: powerful Python data analysis toolkit, Release 0.25.1 • Bug in DataFrame.join() where joining a timezone aware index with a timezone aware column would result in a column of NaN