df.index in python code example

Example 1: pandas index

How to add index to the DataFrame at runtime

df["patient"] = ["patient-" + str( i ) for i in range( max( df.index ) + 1  )]
df.set_index( "patient", inplace=True )
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patient = pandas.Series( ["patient-" + str( i ) for i in range( max( df.index ) + 1 )] )
df.index = patient
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df.index = ["patient-" + str( i ) for i in range( max( df.index ) + 1 )]

Example 2: pandas df by row index

indices = [133, 22, 19, 203, 14, 1]
df_by_indices = df.iloc[indices, :]

Example 3: df.index

The index (row labels) of the DataFrame.

Example 4: add an index column in range dataframe

df = df.loc[df.index.repeat(df['a'])]   
df['c'] = df.groupby(level=0).cumcount() + 1
df = df.reset_index(drop=True)
print (df)
   a  b  c
0  1  x  1
1  2  y  1
2  2  y  2
3  3  z  1
4  3  z  2
5  3  z  3

Example 5: indexing column in pandas

In [8]: age_sex = titanic[["Age", "Sex"]]

In [9]: age_sex.head()
Out[9]: 
    Age     Sex
0  22.0    male
1  38.0  female
2  26.0  female
3  35.0  female
4  35.0    male

Example 6: indexing column in pandas

In [10]: type(titanic[["Age", "Sex"]])
Out[10]: pandas.core.frame.DataFrame