Home » Python » How to reset index in a pandas data frame?

How to reset index in a pandas data frame?

Posted by: admin November 1, 2017 Leave a comment

Questions:

I have a data frame from which I remove some rows. As a result, I get a data frame in which index is something like that: [1,5,6,10,11] and I would like to reset it to [0,1,2,3,4]. How can I do it?

ADDED

The following seems to work:

df = df.reset_index()
del df['index']

The following does not work:

df = df.reindex()
Answers:

reset_index() is what you’re looking for. If you don’t want it saved as a column, then do:

df = df.reset_index(drop=True)

Questions:
Answers:

Another solutions are assign RangeIndex or range:

df.index = pd.RangeIndex(len(df.index))

df.index = range(len(df.index))

It is faster:

df = pd.DataFrame({'a':[8,7], 'c':[2,4]}, index=[7,8])
df = pd.concat([df]*10000)
print (df.head())

In [298]: %timeit df1 = df.reset_index(drop=True)
The slowest run took 7.26 times longer than the fastest. This could mean that an intermediate result is being cached.
10000 loops, best of 3: 105 µs per loop

In [299]: %timeit df.index = pd.RangeIndex(len(df.index))
The slowest run took 15.05 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 7.84 µs per loop

In [300]: %timeit df.index = range(len(df.index))
The slowest run took 7.10 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 14.2 µs per loop