Answers for "how to assign columns pandas"

how to add a column to a pandas df

#using the insert function:
df.insert(location, column_name, list_of_values) 
#example
df.insert(0, 'new_column', ['a','b','c'])
#explanation:
#put "new_column" as first column of the dataframe
#and puts 'a','b' and 'c' as values

#using array-like access:
df['new_column_name'] = value

#df stands for dataframe

python add columns to dataframe without changing the original

#given an original pandas.DataFrame named 'df', and the data series that we want to associate with the new column named 's', 3 possible solutions:

#1-Use "assign()" to create new column and then assign values to it
df_w_new_col = df.assign (name='New_Col')

#2-create an aditional Dataframe with just the new column to add and concatenate with the old dataframe. Like a great majority of pandas methods, this actually creates a new df, it does not just concatenate to the old one so it is safe to change the old and new df's independetly
df = pd.concat( [df, pd.DataFrame({'New_Col:s})], axis=1 )

#3-explicitely create a copy and append a column
df2 = df.copy()
df2['New_Col'] = s