How To Change M D Y To Y-m-d In R

R Programming

Changing the date format from month-day-year (m d y) to year-month-day (y-m-d) in R can be a common requirement when dealing with date-related data. I’ve encountered this need numerous times, especially when working with different datasets that use varying date formats. Luckily, R provides convenient functions to help us achieve this transformation effortlessly. In this article, I’ll walk you through the process of changing the date format in R, sharing my personal insights and tips along the way.

Understanding the Date Format in R

Before delving into the process of changing the date format, it’s essential to understand how dates are represented in R. In R, dates are typically stored as character or factor strings, and transforming these strings from one format to another involves using the as.Date() function. This function allows us to convert character data to Date class data, making it an essential tool in our date format conversion journey.

Step-by-Step Guide to Changing the Date Format

Now, let’s dive into the practical steps of changing the date format from m d y to y-m-d in R:

  1. Load the Dataset: Begin by loading the dataset containing the date column that needs to be transformed. This could be a CSV file, a database table, or any other data source.
  2. Inspect the Current Date Format: It’s crucial to examine the current structure of the date column to ascertain its existing format. This step helps in understanding the data and planning the format conversion process accordingly.
  3. Use as.Date() Function: Apply the as.Date() function to the date column, specifying the current date format using the format parameter. For example, if the current format is m d y, you would use as.Date(date_column, format = "%m %d %y").
  4. Reformat the Date Column: After using the as.Date() function, you will notice that the date column has been converted to the Date class. To change the output format to y-m-d, simply use the format() function on the date column. This will reformat the dates as per the desired structure.
  5. Verify the Changes: It’s good practice to verify the changes and ensure that the date column now reflects the y-m-d format. This can be done by inspecting the first few rows of the updated date column.

Personal Touch: Efficiency and Flexibility

Throughout my experience with date format conversions in R, I’ve found this process to be highly efficient and flexible. The ability to specify the input format in the as.Date() function provides a great level of control, allowing for seamless transformation of dates in various formats. Additionally, the format() function empowers us to tailor the output format to suit specific requirements, making the entire process remarkably adaptable.


In conclusion, mastering the art of changing date formats in R opens up a world of possibilities when working with diverse datasets. By leveraging the as.Date() and format() functions, we can effortlessly transition between different date representations, ensuring that our data aligns with our analytical needs. Remember, understanding the existing date format, utilizing the appropriate functions, and verifying the output are key steps in this transformation journey. Happy coding!