Error: "No method asJSON S3 class: yearmon" occurs when loading or adding a yearmon class column

Questions
#1

The following error may occur when processing or displaying data:

Error : No method asJSON S3 class: yearmon

Causes and Solutions

1. Cause

This error occurs because the data contains a special format called the “yearmon” class.

  • What is the yearmon class?: It is a data type specifically for time series data that only holds year and month information (e.g., “Jan 2024”), commonly used in packages such as “zoo.”
  • Reason for the error: Exploratory cannot directly handle the yearmon class during JSON conversion, which is required for UI display and internal processing. Therefore, the error above is returned, indicating that no conversion method has been defined for this class.

2. Solution

When using functions like ts_to_tbl() from the healthyR.ts package, the date column (often named “index”) is generated as a yearmon class. You can resolve this by explicitly converting this column to a Date class.

3. Specific Correction Steps

If you are using an R script, add the following code to the end of your pipe operator (%>%):

mutate(index = zoo::as.Date(index))
  • Please write it as zoo::as.Date(index) rather than just as.Date(index). This ensures that the conversion from yearmon to Date class is performed reliably, regardless of the execution environment.
  • If the column name is something other than “index,” please rename it accordingly in the code.