Pandas Joining and merging DataFrame : Exercises, Practice, Solution

Last update on April 03 2025 12:54:10 (UTC/GMT +8 hours)

This resource offers a total of 75 Pandas Joining and merging DataFrame problems for practice. It includes 15 main exercises, each accompanied by solutions, detailed explanations, and four related problems.

[An Editor is available at the bottom of the page to write and execute the scripts.]

1. Join DataFrames along Rows (Join Rows)

Write a Pandas program to join the two given dataframes along rows and assign all data.

Test Data:

student_data1:
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

student_data2:
  student_id              name  marks
0         S4  Scarlette Fisher    201
1         S5  Carla Williamson    200
2         S6       Dante Morse    198
3         S7    Kaiser William    219
4         S8   Madeeha Preston    201

2. Join DataFrames along Columns (Join Columns)

Write a Pandas program to join the two given dataframes along columns and assign all data.

Test Data:

student_data1:
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

student_data2:
  student_id              name  marks
0         S4  Scarlette Fisher    201
1         S5  Carla Williamson    200
2         S6       Dante Morse    198
3         S7    Kaiser William    219
4         S8   Madeeha Preston    201

3. Append Rows to Existing DataFrame

Write a Pandas program to append rows to an existing DataFrame and display the combined data.

Test Data:

tudent_data1
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

New Row(s)
student_id                  S6
name          Scarlette Fisher
marks                      205
dtype: object

4. Append List of Dictionaries/Series

Write a Pandas program to append a list of dictioneries or series to a existing DataFrame and display the combined data.

Test Data:

  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

Dictionary:
student_id                  S6
name          Scarlette Fisher
marks                      205
dtype: object

5. Join Rows and Merge with Another DataFrame

Write a Pandas program to join the two given dataframes along rows and merge with another dataframe along the common column id.

Test Data:

student_data1:
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

student_data2:
  student_id              name  marks
0         S4  Scarlette Fisher    201
1         S5  Carla Williamson    200
2         S6       Dante Morse    198
3         S7    Kaiser William    219
4         S8   Madeeha Preston    201

exam_data:
   student_id  exam_id
0          S1       23
1          S2       45
2          S3       12
3          S4       67
4          S5       21
5          S7       55
6          S8       33
7          S9       14
8         S10       56
9         S11       83
10        S12       88
11        S13       12

6. Join DataFrames Using Common Column –

Write a Pandas program to join the two dataframes using the common column of both dataframes.

Test Data:

student_data1:
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

student_data2:
  student_id              name  marks
0         S4  Scarlette Fisher    201
1         S5  Carla Williamson    200
2         S6       Dante Morse    198
3         S7    Kaiser William    219
4         S8   Madeeha Preston    201

7. Join with Matching Records (Inner Join)

Write a Pandas program to join the two dataframes with matching records from both sides where available.

Test Data:

student_data1:
  student_id              name  marks
0         S1  Danniella Fenton    200
1         S2      Ryder Storey    210
2         S3      Bryce Jensen    190
3         S4         Ed Bernal    222
4         S5       Kwame Morin    199

student_data2:
  student_id              name  marks
0         S4  Scarlette Fisher    201
1         S5  Carla Williamson    200
2         S6       Dante Morse    198
3         S7    Kaiser William    219
4         S8   Madeeha Preston    201

8. Left Join Using Keys from Left DataFrame

Write a Pandas program to join (left join) the two dataframes using keys from left dataframe only.

Test Data:

data1:
  key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3

data2:
  key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

9. Right Join Using Keys from Right DataFrame

Write a Pandas program to join two dataframes using keys from right dataframe only.

Test Data:

data1:
  key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3

data2:
  key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

10. Merge Using Multiple Join Keys

Write a Pandas program to merge two given datasets using multiple join keys.

Test Data:

data1:
  key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3

data2:
  key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

11. Create New DataFrame from Existing Series

Write a Pandas program to create a new DataFrame based on existing series, using specified argument and override the existing columns names.

Click me to see the sample solution

12. Combine DataFrames with Duplicate Key Combinations

Write a Pandas program to create a combination from two dataframes where a column id combination appears more than once in both dataframes.

Test Data:

data1:
  key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3

data2:
  key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

13. Combine Columns from Differently-Indexed DataFrames

Write a Pandas program to combine the columns of two potentially differently-indexed DataFrames into a single result DataFrame.

Test Data:

data1:
     A   B
K0  A0  B0
K1  A1  B1
K2  A2  B2

data2:
     C   D
K0  C0  D0
K2  C2  D2
K3  C3  D3

14. Merge DataFrames with Different Columns

Write a Pandas program to merge two given dataframes with different columns.

Test Data:

data1:
  key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3

data2:
  key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

15. Combine DataFrames by Filling Nulls from Another

Write a Pandas program to Combine two DataFrame objects by filling null values in one DataFrame with non-null values from other DataFrame.

Test Data:

Original DataFrames:
     A  B
0  NaN  3
1  0.0  4
2  NaN  5

   A    B
0  1  3.0
1  1  NaN
2  3  3.0

Python Code Editor:

More to Come !

Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.

Test your Python skills with w3resource's quiz