Pandas adding a row into a DataFrame

Question

I am writing a little function that would incrementaly add rows into a DataFrame using pandas.
The core goes like this:

DB =  pd.DataFrame(columns=['MAN','MOD','YEAR','TYPE']) 
for id, row is other_dataFrame.iterrows():
    DB = pd.concat([self.loadedDB, row.to_frame().T])

using print, I get that initial DB looks like this:

Empty DataFrame
Columns: [MAN, MOD, YEAR, TYPE]
Index: []

while row may look like this:

MAN      Aixam
 MOD       400
 YEAR     1930
 TYPE      NaN
Name: 0, dtype: object

then, after the loop the resulting DB looks like this:

           MAN  MOD YEAR TYPE             MOD  YEAR  TYPE
0        Aixam  NaN  NaN  NaN             400  1930   NaN
1          BMW  NaN  NaN  NaN              I3  1930   NaN
2      Bollore  NaN  NaN  NaN         Bluecar  1930   NaN
3          BYD  NaN  NaN  NaN              e6  1930   NaN
4        Buddy  NaN  NaN  NaN             Cab  1930   NaN
5        Chery  NaN  NaN  NaN             QQ3  1930   NaN
6    Chevrolet  NaN  NaN  NaN        Spark EV  1930   NaN
7      Dynasty  NaN  NaN  NaN              IT  1930   NaN
8         Ford  NaN  NaN  NaN  Focus Electric  1930   NaN
...

while I would, of course, like to have it in format of:

           MAN  MOD  YEAR  TYPE
0        Aixam  400  1930   NaN
1          BMW  I3  1930   NaN
2      Bollore  Bluecar  1930   NaN
3          BYD  e6  1930   NaN
4        Buddy  Cab  1930   NaN
5        Chery  QQ3  1930   NaN
6    Chevrolet  Spark EV  1930   NaN
7      Dynasty  IT  1930   NaN
8         Ford  Focus Electric  1930   NaN
...

Can anyone please tell me what am I doing wrong? This is the first time I use pandas, so it is possible that the answer is really simple, however I cant find it. Thank you

Asked By: Adam

||

Source

Answer 1

This should work:

DB =  pd.DataFrame(columns=['MAN','MOD','YEAR','TYPE']) 
for id, row in other_dataFrame.iterrows():
    DB.loc[len(DB)] = [row['MAN'], row['MOD'], row['YEAR'], row['TYPE']]

Just appending a list to the empty dataframe at its last position. There may be an easier way to convert the row object to list, couldn’t find it.

Answered By: datasor

Answer 2

Your original code should work. You should try printing self.loadedDB.columns and row.to_frame().T.columns to verify if there’s any whitespace in these column names, causing them to be concatenated as separate columns.

Answered By: Xnot

Pandas adding a row into a DataFrame

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