Пример текстового файла
text [21-03-1991] 1 Aufgrund O O 2 des O O # text [22-04-1991] 1 Aber O P
text [21-04-1992] 2 Aufgrund O O 3 des O O # text [22-04-1992] 1 Aber O P
text [21-06-1993] 3 Aufgrund O O 5 des O O # text [22-04-1993] 1 Aber O P
import pandas as pd
# Reading tab separated text file
df = pd.read_csv("source.txt",sep='\t')
df1 = df.iloc[:,[3,4,5]]
df1.columns = ['V1','V2','V3']
df2 = df.iloc[:,[7,8,9]]
df2.columns = ['V1','V2','V3']
df3 = df.iloc[:,[14,15,16]]
df3.columns = ['V1','V2','V3']
d_one = df1.append(df2, ignore_index=True)
final_df = d_one.append(df3, ignore_index=True)
print(final_df)