﻿ Pandas: Merge two dataframes with different columns - w3resource # Pandas: Merge two dataframes with different columns

## Pandas Joining and merging DataFrame: Exercise-14 with Solution

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
```

Sample Solution:

Python Code :

``````import pandas as pd
data1 = pd.DataFrame({'key1': ['K0', 'K0', 'K1', 'K2'],
'key2': ['K0', 'K1', 'K0', 'K1'],
'P': ['P0', 'P1', 'P2', 'P3'],
'Q': ['Q0', 'Q1', 'Q2', 'Q3']})
data2 = pd.DataFrame({'key1': ['K0', 'K1', 'K1', 'K2'],
'key2': ['K0', 'K0', 'K0', 'K0'],
'R': ['R0', 'R1', 'R2', 'R3'],
'S': ['S0', 'S1', 'S2', 'S3']})
print("Original DataFrames:")
print(data1)
print("--------------------")
print(data2)
print("\nMerge two dataframes with different columns:")
result = pd.concat([data1,data2], axis=0, ignore_index=True)
print(result)
``````

Sample Output:

```Original DataFrames:
key1 key2   P   Q
0   K0   K0  P0  Q0
1   K0   K1  P1  Q1
2   K1   K0  P2  Q2
3   K2   K1  P3  Q3
--------------------
key1 key2   R   S
0   K0   K0  R0  S0
1   K1   K0  R1  S1
2   K1   K0  R2  S2
3   K2   K0  R3  S3

Merge two dataframes with different columns:
P    Q    R    S key1 key2
0   P0   Q0  NaN  NaN   K0   K0
1   P1   Q1  NaN  NaN   K0   K1
2   P2   Q2  NaN  NaN   K1   K0
3   P3   Q3  NaN  NaN   K2   K1
4  NaN  NaN   R0   S0   K0   K0
5  NaN  NaN   R1   S1   K1   K0
6  NaN  NaN   R2   S2   K1   K0
7  NaN  NaN   R3   S3   K2   K0
```

Python Code Editor:

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## Python: Tips of the Day

For-else construct useful when searched for something and find it:

```# For example assume that I need to search through a list and process each item until a flag item is found and
# then stop processing. If the flag item is missing then an exception needs to be raised.

for i in mylist:
if i == theflag:
break
process(i)
else:
raise ValueError("List argument missing terminal flag.")
```