How to Merge two Pandas DataFrames with Complex Conditions

Conditional merging in pandas refers to merging two or more DataFrames based on a specific condition. This differs from regular merging, typically based on one or more common columns (keys) between the DataFrames. 

There are a few ways to perform conditional merging of pandas DataFrames: 

• Using pd.concat() function with a filter: You can use the pd.concat() function to concatenate the DataFrames and then use a filter to select only the rows that meet the specified condition. 
• Using loc[] or iloc[] to filter DataFrames before merging: You can use the loc[] or iloc[] method to select the rows that meet the specified condition and then merge the filtered DataFrames. 
• Using merge() with a left_on and right_on parameter: This method allows merging the DataFrames on different columns and with different conditions. 

It's also worth mentioning that the above solutions are based on simple conditions. If you need to merge Dataframes based on more complex conditions, it may be better to use the "query()" method or create a mask using boolean operations and apply it to the dataframe before merging. 

For more information about the conditional merging of Pandas DataFrame please look at the code below. 

Fig : Preview of the output that you will get on running this code from your IDE.

Code

In this solution we're using Pandas library.

Instructions

Follow the steps carefully to get the output easily.

1. Install pandas on your IDE(Any of your favorite IDE).
2. Copy the snippet using the 'copy' and paste it in your IDE.
3. Add required dependencies and import them in Python file(import pandas).
4. Add print statement at end of the code(refer preview of the output).
5. Run the file to generate the output.

I hope you found this useful. I have added the link to dependent libraries, version information in the following sections.

I found this code snippet by searching for 'how to conditional merging of pandas dataframes' in kandi. You can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

1. The solution is created in PyCharm 2021.3.
2. The solution is tested on Python 3.9.7.
3. Pandas version-v1.5.2.

Using this solution, we are able to merge dataframes of pandas based on conditions with simple steps. This process also facilities an easy way to use, hassle-free method to create a hands-on working version of code which would help us to merge dataframes of pandas based on conditions.

Dependent Library

You can also search for any dependent libraries on kandi like 'pandas'.

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