8000 Doc: Adds example of exploding lists into columns instead of storing in dataframe cells by mgautam98 · Pull Request #23041 · pandas-dev/pandas · GitHub
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Doc: Adds example of exploding lists into columns instead of storing in dataframe cells #23041

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Doc: Adds example of exploding lists into columns instead of storing in dataframe cells #23041

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e91444e
DOC: Adds example of alternative to storing lists in a Dataframe
Jan 12, 2018
11ff8a7
Doc: Fixes issues with code examples.
Jan 12, 2018
7ca0ce8
Merge remote-tracking branch 'upstream/master' into doc-gotchas-17027
mgautam98 Oct 8, 2018
6d379b4
DOC: Add example of alternative to storing lists in a Dataframe fix P…
mgautam98 Oct 8, 2018
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DOC: Adds example of alternative to storing lists in a Dataframe - ma…
mgautam98 Oct 8, 2018
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Doc: Adds example of exploding lists into columns instead of storing …
mgautam98 Oct 8, 2018
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Doc: Adds example of exploding lists into columns instead of storing … 
…in dataframe cells
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@mgautam98
mgautam98 committed Oct 8, 2018
commit 4952597f4a94a4e21a5ec72fd8d5fef2dfa81a5f
36 changes: 8 additions & 28 deletions doc/source/gotchas.rst
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Expand Up @@ -346,10 +346,10 @@ Example of exploding nested lists into a DataFrame:

.. ipython:: python

dframe = pd.DataFrame({'name': ['A.J. Price'] * 3,
df = pd.DataFrame({'name': ['A.J. Price'] * 3,
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I believe this is copied from the following SO article:

https://stackoverflow.com/questions/32468402/how-to-explode-a-list-inside-a-dataframe-cell-into-separate-rows

Need to be careful copy / pasting items from SO into the code base. Would have to get express permission from author to use

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@TomAugspurger TomAugspurger Oct 8, 2018 •
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I think SO code snippets are CC BY-SA so as long as we link back to the source (which we should be doing anything) then we're good.

https://stackoverflow.com/help/licensing

'opponent': ['76ers', 'blazers', 'bobcats']},
columns=['name','opponent'])
dframe
columns=['name','opponent'])
df

nearest_neighbors = [['Zach LaVine', 'Jeremy Lin', 'Nate Robinson', 'Isaia']]*3
nearest_neighbors
Expand All @@ -358,7 +358,7 @@ Create an index with the "parent" columns to be included in the final Dataframe

.. ipython:: python

df = pd.concat([dframe[['name','opponent']], pd.DataFrame(nearest_neighbors)], axis=1)
df = pd.concat([df[['name','opponent']], pd.DataFrame(nearest_neighbors)], axis=1)
df

Transform the column with lists into series, which become columns in a new Dataframe.
Expand All @@ -385,32 +385,22 @@ Note that at this point we have a Series, not a Dataframe
df = ser.to_frame('nearest_neighbors')
df

All steps in one stack

.. ipython:: python

df = (dframe.concat([df[['name','opponent']], pd.DataFrame(nearest_neighbors)], axis=1)
.set_index(['name', 'opponent'])
.stack()
.reset_index(level=2, drop=True)
.to_frame('nearest_neighbors'))
df

Example of exploding a list embedded in a dataframe:

.. ipython:: python

dframe = pd.DataFrame({'name': ['A.J. Price'] * 3,
df = pd.DataFrame({'name': ['A.J. Price'] * 3,
'opponent': ['76ers', 'blazers', 'bobcats'],
'nearest_neighbors': [['Zach LaVine', 'Jeremy Lin', 'Nate Robinson', 'Isaia']] * 3},
columns=['name','opponent','nearest_neighbors'])
dframe
columns=['name','opponent','nearest_neighbors'])
df

Create an index with the "parent" columns to be included in the final Dataframe

.. ipython:: python

df = dframe.set_index(['name', 'opponent'])
df = df.set_index(['name', 'opponent'])
df

Transform the column with lists into series, which become columns in a new Dataframe.
Expand All @@ -437,13 +427,3 @@ Note that at this point we have a Series, not a Dataframe
df = ser.to_frame('nearest_neighbors')
df

All steps in one stack

.. ipython:: python

df = (dframe.set_index(['name', 'opponent'])
.nearest_neighbors.apply(pd.Series)
.stack()
.reset_index(level=2, drop=True)
.to_frame('nearest_neighbors'))
df
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