Pandas Dataframe adding muliple empty row issue-CodePudding

I have test the code to add multiple empty row to Pandas DataFrame it worked.

import pandas as pd

df = pd.DataFrame({'name': ["James", "White", "John"],
                   'rebounds': [7, 7, 8]})

for i in range(100):
    dft =  df.columns.values.tolist()
    s = pd.Series(dft)
    df.loc[len(df)] =s
print(len(df.index))

In my application I have this code, its adding 16 empty rows but it adds only 4 rows.

    print(f"Before adding {len(df3.index)}")
    dft =  df3.columns.values.tolist()
    s = pd.Series(dft)
    for i in range(16):
        df3.loc[len(df3)] =s

    print(f"After adding {len(df3.index)}")

Output

Before adding 221
After adding 225

why its not adding 16 empty rows in my application code? How to troubleshoot this issue?

Thanks

CodePudding user response：

You might have duplicated indices. For example if you array has 221 rows but an indice 222, no row will be added.

A more robust method could be to concat:

N = 4
df = pd.concat([df, pd.DataFrame(columns=df.columns,
                                 index=range(len(df), len(df) N))
                ])

output:

    name rebounds
0  James        7
1  White        7
2   John        8
3    NaN      NaN
4    NaN      NaN
5    NaN      NaN
6    NaN      NaN