thisisnic commented on a change in pull request #76:
URL: https://github.com/apache/arrow-cookbook/pull/76#discussion_r719367995
##########
File path: python/source/data.rst
##########
@@ -137,3 +137,48 @@ function
.. testoutput::
0 .. 198
+
+Appending tables to an existing table
+=====================================
+
+If you have data split in two different tables, it's possible
+to combine them into a single table that is the concatenation
+of the original tables.
+
+If we have the list of oscar nominations divided in two different tables:
Review comment:
```suggestion
If we have the list of Oscar nominations divided between two different
tables:
```
##########
File path: python/source/data.rst
##########
@@ -137,3 +137,48 @@ function
.. testoutput::
0 .. 198
+
+Appending tables to an existing table
+=====================================
+
+If you have data split in two different tables, it's possible
+to combine them into a single table that is the concatenation
+of the original tables.
+
+If we have the list of oscar nominations divided in two different tables:
+
+.. testcode::
+
+ import pyarrow as pa
+
+ oscar_nominations_1 = pa.table([
+ ["Meryl Streep", "Katharine Hepburn"],
+ [21, 12]
+ ], names=["actor", "nominations"])
+
+ oscar_nominations_2 = pa.table([
+ ["Jack Nicholson", "Bette Davis"],
+ [12, 10]
+ ], names=["actor", "nominations"])
+
+We can join them into a single one using :func:`pyarrow.concat_tables`:
Review comment:
Swapped "join" for "combine" to make it clear we're not talking about
SQL-style joins
```suggestion
We can combine them into a single table using :func:`pyarrow.concat_tables`:
```
##########
File path: python/source/data.rst
##########
@@ -137,3 +137,48 @@ function
.. testoutput::
0 .. 198
+
+Appending tables to an existing table
+=====================================
+
+If you have data split in two different tables, it's possible
+to combine them into a single table that is the concatenation
+of the original tables.
+
+If we have the list of oscar nominations divided in two different tables:
+
+.. testcode::
+
+ import pyarrow as pa
+
+ oscar_nominations_1 = pa.table([
+ ["Meryl Streep", "Katharine Hepburn"],
+ [21, 12]
+ ], names=["actor", "nominations"])
+
+ oscar_nominations_2 = pa.table([
+ ["Jack Nicholson", "Bette Davis"],
+ [12, 10]
+ ], names=["actor", "nominations"])
+
+We can join them into a single one using :func:`pyarrow.concat_tables`:
+
+.. testcode::
+
+ oscar_nominations = pa.concat_tables([oscar_nominations_1,
+ oscar_nominations_2])
+
+ print(oscar_nominations.to_pydict())
+
+.. testoutput::
+
+ {'actor': ['Meryl Streep', 'Katharine Hepburn', 'Jack Nicholson', 'Bette
Davis'], 'nominations': [21, 12, 12, 10]}
+
+.. note::
+
+ By default appending two tables is a zero-copy operation, that doesn't need
to
+ copy or rewrite data. As tables are made of :class:`pyarrow.ChunkedArray`
+ the result will be a table with multiple chunks, each pointing to the
original
+ data that has been appended. Under some conditions, Arrow might have to
+ do casts (if `promote=True`) and in such cases the data will need to be
copied
+ and an extra cost will occurr.
Review comment:
```suggestion
By default, appending two tables is a zero-copy operation that doesn't
need to
copy or rewrite data. As tables are made of :class:`pyarrow.ChunkedArray`,
the result will be a table with multiple chunks, each pointing to the
original
data that has been appended. Under some conditions, Arrow might have to
cast data from one type to another (if `promote=True`). In such cases the
data
will need to be copied and an extra cost will occur.
```
##########
File path: python/source/data.rst
##########
@@ -137,3 +137,48 @@ function
.. testoutput::
0 .. 198
+
+Appending tables to an existing table
+=====================================
+
+If you have data split in two different tables, it's possible
+to combine them into a single table that is the concatenation
+of the original tables.
Review comment:
Added explicit mention of rows to make sure it's clear this isnt' about
columns.
```suggestion
If you have data split across two different tables, it is possible
to concatenate their rows into a single table.
```
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