How to convert index of a pandas dataframe into a column?
either:
df['index1'] = df.index
or, .reset_index
:
df = df.reset_index(level=0)
so, if you have a multi-index frame with 3 levels of index, like:
>>> df
val
tick tag obs
2016-02-26 C 2 0.0139
2016-02-27 A 2 0.5577
2016-02-28 C 6 0.0303
and you want to convert the 1st (tick
) and 3rd (obs
) levels in the index into columns, you would do:
>>> df.reset_index(level=['tick', 'obs'])
tick obs val
tag
C 2016-02-26 2 0.0139
A 2016-02-27 2 0.5577
C 2016-02-28 6 0.0303
rename_axis
+ reset_index
You can first rename your index to a desired label, then elevate to a series:
df = df.rename_axis('index1').reset_index()
print(df)
index1 gi ptt_loc
0 0 384444683 593
1 1 384444684 594
2 2 384444686 596
This works also for MultiIndex
dataframes:
print(df)
# val
# tick tag obs
# 2016-02-26 C 2 0.0139
# 2016-02-27 A 2 0.5577
# 2016-02-28 C 6 0.0303
df = df.rename_axis(['index1', 'index2', 'index3']).reset_index()
print(df)
index1 index2 index3 val
0 2016-02-26 C 2 0.0139
1 2016-02-27 A 2 0.5577
2 2016-02-28 C 6 0.0303
To provide a bit more clarity, let's look at a DataFrame with two levels in its index (a MultiIndex).
index = pd.MultiIndex.from_product([['TX', 'FL', 'CA'],
['North', 'South']],
names=['State', 'Direction'])
df = pd.DataFrame(index=index,
data=np.random.randint(0, 10, (6,4)),
columns=list('abcd'))
The reset_index
method, called with the default parameters, converts all index levels to columns and uses a simple RangeIndex
as new index.
df.reset_index()
Use the level
parameter to control which index levels are converted into columns. If possible, use the level name, which is more explicit. If there are no level names, you can refer to each level by its integer location, which begin at 0 from the outside. You can use a scalar value here or a list of all the indexes you would like to reset.
df.reset_index(level='State') # same as df.reset_index(level=0)
In the rare event that you want to preserve the index and turn the index into a column, you can do the following:
# for a single level
df.assign(State=df.index.get_level_values('State'))
# for all levels
df.assign(**df.index.to_frame())