I need to insert null values for missing index in python pandas

Question

I have a dataset

x  text
1  one
2  two
4  four
5  five
7  seven

now I want output as

x  text
1  one
2  two
3  null
4  four
5  five
6  null
7  seven

Answer 1

Use reindex:

#if x is column
#df = df.set_index('x').reindex(np.arange(df.index.min(), df.index.max() + 1))
#if x is index
df = df.reindex(np.arange(df.index.min(), df.index.max() + 1))
print (df)
    text
x       
1    one
2    two
3    NaN
4   four
5   five
6    NaN
7  seven