`bm_extract`: Incorrect Day of Year (DOY) calculation for VNP46A3 URLs (Leap Year Logic Inverted?)

[aidanhorn]

I am encountering 404 errors when downloading VNP46A3 (monthly) data because bm_extract generates incorrect URLs for the .csv files. It appears the "Day of Year" (DOY) calculation is off by one day: it seems to treat leap years as non-leap years, and non-leap years as leap years.

Package Version

0.2.5

Examples

1. Leap Year (2024)

   • Date: 2024-09-01
   • Actual DOY: 245
   • Generated URL: .../2024/244.csv (DOY 244)
   • Result: 404 Error (File not found).
   • Observation: It behaves as if February had 28 days.

2. Non-Leap Year (2025)

   • Date: 2025-04-01
   • Actual DOY: 91
   • Generated URL: .../2025/092.csv (DOY 92)
   • Result: 404 Error.
   • Observation: It behaves as if February had 29 days.

Minimal Reproducible Example

library(blackmarbler)
library(sf)

# Dummy ROI
roi <- st_as_sf(data.frame(id=1, lat=0, lon=0), coords = c("lon", "lat"), crs=4326)

# Case 1: Leap Year (2024) - calculated DOY is one too low (244 vs 245)
try(bm_extract(roi_sf=roi, product_id="VNP46A3", date="2024-09-01", bearer="MY_TOKEN"))

# Case 2: Non-Leap Year (2025) - calculated DOY is one too high (092 vs 091)
 try(bm_extract(roi_sf=roi, product_id="VNP46A3", date="2025-04-01", bearer="MY_TOKEN"))