Subsetting RasterStack based on String Partial Match

Question

I have a RasterStack with 191 layers with the following naming convention:

[1] "LC08_L1TP_037035_20130501_20170310_01_T1_sr_ndvi" "LC08_L1TP_037035_20130602_20170310_01_T1_sr_ndvi"

...

I also have a separate data.frame (df_filtered) that contains a list of these rasters after a set of filtering conditions were applied, resulting in 161 rasters. The file names listed in df_filtered, however, have a slightly different naming convention, where the last part ("_sr_ndvi") of the file name was dropped:

  ID
1 LC08_L1TP_037035_20130501_20170310_01_T1 
2 LC08_L1TP_037035_20130602_20170310_01_T1

I would like to subset the original stack of 191 rasters to only include those listed in df_filtered. My approach was to use use grep to conduct a partial match. Here is the code I tried:

rasters_filtered <- raster::subset(my_stack, grep(df_filtered$ID, names(my_stack), value = T))

This works for the first raster in the stack, but not for the rest. Here is the error: "argument 'pattern' has length > 1 and only the first element will be used"

Is there a way to have it iterate through all the names in the list?

Baltazar González Chávez Baltazar González Chávez · Accepted Answer · 2020-06-23T17:42:13

Maybe you could do something like:

names(my_stack) <- gsub('_sr_ndvi', '', names(my_stack)) #to eliminate suffix in the stack

raster_filtered <- raster::subset(my_stack, df_filtered$ID)

Subsetting RasterStack based on String Partial Match

1 Answers