Concat pandas dataframes in Python with different row size without getting NaN values

I have to combine some dataframes in Python. I’ve tried to combine them using concat operation, but I am getting NaN values because each dataframe has different row size. For example:

DATAFRAME 1:
   col1     
0     1     
DATAFRAME 2:
   col2     
0     5     
DATAFRAME 3:
   col3
0     7
1     8
2     9
COMBINED DATAFRAME: 
   col1  col2  col3 
0   1.0   5.0     7 
1   NaN   NaN     8 
2   NaN   NaN     9

In this example, dataframe 1 and dataframe 2 only have 1 row. However, dataframe 3 has 3 rows. When I combine these 3 dataframes, I get NaN values for columns col1 and col2 in the new dataframe. I’d like to get a dataframe where the values for col1 and col2 are always the same. In this case, the expected dataframe would look like this:

EXPECTED DATAFRAME:
   col1  col2  col3
0     1     5     7
1     1     5     8
2     1     5     9

Any idea? Thanks in advance

Answer

Use concat and ffill:

df = pd.concat([df1, df2, df3], axis=1).fill()