Data aggregation is one huge Data Scientist job. More times than I can remember, I ended up with multiple files that I had to aggregate.

Aggregation can be very helpful when you want to compare results against a certain variable. (e.g. Sales per month over a few years but you only have yearly sales reports).

Enough talking

Here is the code

How to combine by rows

# Append two dataframes (add the rows of a dataframe to another one)
# To work with dataframes
import pandas as pd

# We create a sample dataframe
df_year_2020 = pd.DataFrame({"Country" : ["Germany", "USA", "France"],
                             "Temperatures" : [3332000000, 
                             			       20839000000,
                                               2603000000],
                             "Year" : [2020, 2020, 2020]})

# We create a second sample dataframe
df_year_2021 = pd.DataFrame({"Country" : ["Germany", "USA", "France"],
                             "Temperatures" : [4218000000, 
                             				   22939000000,
                                               2785210000],
                             "Year" : [2021, 2021, 2021]})

# We append the two dataframes using the concat method
df_combined_rows = pd.concat([df_year_2020, 
 							  df_year_2021])

How to combine two DataFrame together by rows

How to combine by columns

# Append two dataframes (add the columns of a dataframe to another one)
# To work with dataframes
import pandas as pd

# We create a sample dataframe
df_student_part_1 = pd.DataFrame({"Student" : ["Albert", 
											   "Francesca", 
                                               "Pierre"],
                                  "Age" : [23, 21, 25]})

# We create a second sample dataframe
df_student_part_2 = pd.DataFrame({"Location" : ["Germany", 
												"USA",
                                                "France"],
                             	  "Grade" : [15, 19, 17]})

# We append the two dataframes using the concat method and we specify the axis columns (axis=1)
df_combined_cols = pd.concat([df_student_part_1, 
						      df_student_part_2], 
                              axis=1)

How to combine two DataFrame together by cols

Here you are! You now know how to combine two DataFrame together either by rows or columns.