在单个数据帧中追加循环输出

Question

I'm trying to append the for loop output in pandas dataframe as:

import pandas as pd
for i in range(1,5):
    p=i+4
    df = pd.DataFrame({'filename':i,'comments':p},index=[0])
    print (df)

It returns as multiple dataframe as:

   filename  comments
0         1         5
   filename  comments
0         2         6
   filename  comments
0         3         7
   filename  comments
0         4         8

Output expected as:

    filename comments
1   1         5
2   2         6
3   3         7
4   4         8

I'm looking to build and fill a dataframe from a loop only

Answer 1

You can append a list as a series to a dataframe like so

import pandas as pd

df = pd.DataFrame(columns=['filename','comments'])
for i in range(1,5):
    df = df.append(pd.Series([i, i+4], index=df.columns), ignore_index=True)

print (df)

you must define the empty dataframe to begin with and then from within the loop append the list as a new row