I wish to use the R package greenbrown to calculate phenology metrics such as Start of Season (SOS) or End of Season (EOS) of Kenya from NDVI values. I already have a panel dataset which includes one datapoint for each 0.5 x 0.5 degrees grid cell for each 16 days since the year 2000 and it looks like the following.
| cell_id | lon | lat | date | year | month | day | period | mean | median |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 33.31259 | -4.76495 | 06apr2000 | 2000 | 4 | 6 | 7 | 5934.126 | 5990.774 |
| 1 | 33.31259 | -4.76495 | 22apr2000 | 2000 | 4 | 22 | 8 | 5648.910 | 5652.855 |
Now as far as I know, I need a object of the class brick (i.e., a multi-layer raster object) to use the greenbrown function PhenologyRaster. However, I have no experience in converting this dataframe into a multi-layer raster object and wasn't able to resolve my issue online.