Pandas dataframe for appending a list or dataframe

Question

How to add a list of values to the end of dataframe that already has values? I tried append without any luck. dataAlkuperainen are pandas csv files that I turned into dataframes. But for some reason appending them wont do anything.

   # collecting data from a csv file
dataAlkuperainen = pd.read_csv("persons_customers_AT.csv", 
sep=";", dtype={"counterparty_id":str, "counterparty_firstname": str, "counterparty_lastname":str, 
"counterparty_type":str, "date_of_birth":str},  encoding='ISO-8859-1', engine = 'python')

dataAlkuperainen2 = pd.read_csv("Organisations_customers_AT.csv", 
sep=";", dtype={"counterparty_id":str, "organisation_name": str},  encoding='ISO-8859-1', engine = 'python')

dateOfBirth = dataAlkuperainen["date_of_birth"]

# creating dataframe with new columns
df = DataFrame(dataAlkuperainen, columns=[ "counterparty_id", "organisation_name" ,"counterparty_firstname", "counterparty_lastname", 
"counterparty_type", "vuosi", "kuukausi", "paiva"], dtype=object)

df2 = DataFrame(dataAlkuperainen2, columns=[ "counterparty_id", "organisation_name"], dtype=object)
df.astype(str)

# slicing date of birth to separate selections
vuosi = []
kk = []
paiva = []
for x in dateOfBirth:
    vuosi.append(x[:4])
    kk.append(x[5:7])
    paiva.append(x[8:10])

idObject = {"ID", "Organisation_name"}
listOfCompanies = []
idx = 0
for x, y in dataAlkuperainen2['counterparty_id'].items():
    idObject = {"ID": y, "Organisation_name": dataAlkuperainen2['organisation_name'][x]}
    listOfCompanies.append(idObject)

df['vuosi'] = vuosi
df['kuukausi'] = kk
df['paiva'] = paiva

df['counterparty_id'].loc[len(df)] = df2['counterparty_id'].values[:df.shape[1]]
export_csv = df.to_csv (r'./test.cvs', index = None, sep=";", header=True, encoding="ISO-8859-1")
print(df2)
print(df)

no I need to add to the end of my dataframe values from another dataframe values to specific column. — Levsha
– Levsha, Commented Aug 18, 2021 at 12:10
can you provide sample dataframe and your expected output from it? — Anurag Dabas
– Anurag Dabas, Commented Aug 18, 2021 at 12:11
What is dataAlkuperainen2? Is it a dictionary, that has the same structure as dataAlkuperainen? If so, then make a DataFrame out of it before append-ing. (You need to provide more information about the structures and also the errors you ran into.) — Timus
– Timus, Commented Aug 18, 2021 at 15:18

user12628549 · Accepted Answer · 2021-08-18 13:13:13Z

0

I suppose, you want to take column from df2 and put it as a row into df1. You can just add a new row. For example, use loc:

Update. Consider different lenghts:

d = {"A":pd.Series([1, 2, 3], index=[1,2,3]), "B": pd.Series([10, 12, 17], index=[1,2,3])}
df1 = pd.DataFrame(d)

df1

    A   B
1   1   10
2   2   12
3   3   17


d = {"B":pd.Series([1, 22, 111], index=[1,2, 3]), "C": pd.Series([0, 0, 0], index=[1,2, 3])}
df2 = pd.DataFrame(d)
df2


    B   C
1   1   0
2   22  0
3   111 0


df1.loc[4] = df2['C'].values[:df1.shape[1]]
df1


    A   B
1   1   10
2   2   12
3   3   17
4   0   0

edited Aug 18, 2021 at 13:13

answered Aug 18, 2021 at 12:27

user12628549

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3 Comments

Levsha Over a year ago

thanks but it didnt work. My code is df.loc[len(df)] = dataAlkuperainen2['counterparty_id'].values but I get ValueError: cannot set a row with mismatched columns error

user12628549 Over a year ago

@Levsha then define the length: df1.loc[4] = df2['C'].values[:df1.shape[1]]

Levsha Over a year ago

this line df.loc[len(df)] = dataAlkuperainen2['counterparty_id'].values[:df.shape[1]] didn't add values at the end of the dataframe. For some reason nothing happened

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