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Learn how to merge two data frames with identical row names and column names in R, concatenating their differing entries into a single data frame.
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How to Merge Two Data Frames into One by Concatenating Entries

If you work with data in R, you might often come across a situation where you have two data frames with identical structures but different entries. You may want to combine these data frames into one, where the entries are concatenated and separated by a specific character, such as a semicolon (;). In this guide, we will explore a straightforward solution to achieve this using only base R functionalities.

The Problem

Consider the following two data frames:

Data Frame 1 (df1)

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Data Frame 2 (df2)

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Your goal is to merge df1 and df2 into a single data frame (df3) with the following structure:

Desired Output Data Frame (df3)

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In the resulting data frame, the individual entries from both df1 and df2 should be concatenated and separated by a semicolon.

The Solution

Method 1: Using Map and paste

Using Map to Concatenate:

You can use the Map function, which applies a function to the corresponding elements of multiple lists or vectors.

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Replacing Entries in df1:

Once you have the concatenated list L, you can replace the entries of df1:

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Alternatively, you can use:

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Or create a new data frame using as.data.frame:

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Output:

After executing the above code, you will get:

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Method 2: Using as.matrix and paste

This method avoids using Map and instead converts the data frames to matrices for concatenation.

Convert to Matrices and Concatenate:

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Replace Entries in df1:

You can then perform the same replacement to obtain the final result:

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Or, if creating an output data frame:

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Conclusion

Merging two data frames by concatenating their entries is straightforward with R, especially using the base functionalities. By employing either the Map or matrix approach, you can effectively combine your data frames to achieve the desired results.

Feel free to try these methods on your own data frames, and happy coding!