Appending a list or series to a pandas DataFrame as a row

Question

So I have initialized an empty pandas DataFrame and I would like to iteratively append lists  or Series  as rows in this DataFrame  What is the best way of doing this

User · Answer

Could you do something like this    gt  gt  gt  import pandas as pd  gt  gt  gt  df   pd DataFrame columns   col1    col2     gt  gt  gt  df   df append pd Series   a    b    index   col1   col2     ignore index True   gt  gt  gt  df   df append pd Series   d    e    index   col1   col2     ignore index True    gt  gt  gt  df   col1 col2 0    a    b 1    d    e   Does anyone have a more elegant solution

User · Answer

There are several ways to append a list to a Pandas Dataframe in Python  Let s consider the following dataframe and list  import pandas as pd   Dataframe df   pd DataFrame   1  2    3  4    columns     quot col1 quot    quot col2 quot      List to append list    5  6   Option 1  append the list at the end of the dataframe with  pandas DataFrame loc  df loc len df     list  Option 2  convert the list to dataframe and append with  pandas DataFrame append    df   df append pd DataFrame  list   columns df columns   ignore index True   Option 3  convert the list to series and append with   pandas DataFrame append     df   df append pd Series list  index   df columns   ignore index True   Each of the above options should output something like   gt  gt  gt  print  df     col1  col2 0     1     2 1     3     4 2     5     6  Reference   How to append a list as a row to a Pandas DataFrame in Python

User · Answer

If you want to add a Series and use the Series  index as columns of the DataFrame  you only need to append the Series between brackets   In  1   import pandas as pd  In  2   df   pd DataFrame    In  3   row pd Series  1 2 3    A   B   C     In  4   row Out 4    A    1 B    2 C    3 dtype  int64  In  5   df append  row  ignore index True  Out 5       A  B  C 0  1  2  3   1 rows x 3 columns    Whitout the ignore index True you don t get proper index

User · Answer

simply use loc    gt  gt  gt  df      A  B  C one  1  2  3  gt  gt  gt  df loc  two      4 5 6   gt  gt  gt  df      A  B  C one  1  2  3 two  4  5  6

User · Answer

Sometimes it s easier to do all the appending outside of pandas  then  just create the DataFrame in one shot    gt  gt  gt  import pandas as pd  gt  gt  gt  simple list    a   b     gt  gt  gt  simple list append   e   f     gt  gt  gt  df pd DataFrame simple list columns   col1   col2       col1 col2 0    a    b 1    e    f

User · Answer

Converting the list to a data frame within the append function works  also when applied in a loop  import pandas as pd mylist    1 2 3  df   pd DataFrame   df   df append pd DataFrame data mylist

User · Answer

As mentioned here - https   kite com python answers how-to-append-a-list-as-a-row-to-a-pandas-dataframe-in-python  you ll need to first convert the list to a series then append the series to dataframe  df   pd DataFrame   1  2    3  4    columns     quot a quot    quot b quot    to append    5  6  a series   pd Series to append  index   df columns  df   df append a series  ignore index True

User · Answer

Here s a function that  given an already created dataframe  will append a list as a new row  This should probably have error catchers thrown in  but if you know exactly what you re adding then it shouldn t be an issue   import pandas as pd import numpy as np  def addRow df ls               Given a dataframe and a list  append the list as a new row to the dataframe        param df   lt DataFrame gt  The original dataframe      param ls   lt list gt  The new row to be added      return   lt DataFrame gt  The dataframe with the newly appended row              numEl   len ls       newRow   pd DataFrame np array ls  reshape 1 numEl   columns   list df columns        df   df append newRow  ignore index True       return df

User · Answer

The simplest way   my list    1 2 3 4 5  df  new column     pd Series my list  values   Edit   Don t forget that the length of the new list should be the same of the corresponding Dataframe

User · Answer

Consider an array A of N x 2 dimensions  To add one more row  use the following  A loc A shape 0      3 4

User · Answer

df   pd DataFrame columns list  ABC    df loc len df      1 2 3

User · Answer

Following onto Mike Chirico s answer     if you want to append a list after the dataframe is already populated      gt  gt  gt  list      f   g     gt  gt  gt  df   df append pd DataFrame list  columns   col1   col2    ignore index True   gt  gt  gt  df   col1 col2 0    a    b 1    d    e 2    f    g

User · Answer

Here s a simple and dumb solution    gt  gt  gt  import pandas as pd  gt  gt  gt  df   pd DataFrame    gt  gt  gt  df   df append   foo  1   bar  2   ignore index True

[python] Appending a list or series to a pandas DataFrame as a row?

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